Squashed commits of the following:

* Delete an unused global (getredash#3231)

Signed-off-by: koooge <[email protected]>

* Fix: forked query wasn't opening in MULTI_ORG env (getredash#3236)

* Send argsrepr value with execute_query task (getredash#3235)

* request.view_args might be None and add org_id to ApiUser (getredash#3237)

* Handle the case when a QueryTracker is None and change order. (getredash#3238)

* Fix: Query editor duplicates keystrokes [getredash#2972] (getredash#3239)

* Simple user view (getredash#3244)

* show a simple user details page when viewing a user who isn't you (or you arent the admin)

* add a snapshot test

* lint

* getredash#3213 Scatter charts can have category Y axis (similar to Bubble) (getredash#3243)

* Upgrade requests package (getredash#3245)

* Support overriding the default Celery schedule database file via SCHEDULE_DB environment variable. (getredash#3056)

By default Celery will use a file celerybeat-schedule in the current directory.
This is an issue in a Kubernetes/Openshift environment as the file may be lost or even impossible to write.

* Closes getredash#2396: Add finer-grained scheduling. (getredash#2426)

* Closes getredash#187: Add finer-grained scheduling - backend.

* Closes getredash#2396 - Add finer-grained scheduling - frontend.

* Fix linting issues

* Rename ScheduleDialgo to .jsx

* Feature: Refresh schedule - code optimizations

* Feature: Refresh schedule - save/cancel actions

* Feature: Refresh schedule - styling (getredash#3247)

* Fix: Able to set out-of-range refresh interval

* Fix: Refresh schedule phrase overlaps title (getredash#3250)

* Add "Active at" column to user list. (getredash#3026)

* add last_active_at to users page

* Use our JSON encoder as the SQLAlchemy JSON serializer.

* Fixed some inconsistencies in the user query class methods.

* Minor cosmetic fixes.

* Add some make tasks for easier development.

* Add user detail sync system based on Redis backend.

There is a periodic Celery task that updates a new “details” JSONB column in the “user” table with the data from Redis.

Currently this is only used for tracking the date of last activity of a user but can be extended with other user information later.

Updates a few dependencies.

* Normalize a few Flask extension API names.

* Reduce implementation complexity of JSONEncoder.

* Use request_started signal to make sure we have a request context.

Otherwise loading the user based on the request won’t work.

* Fix test that checks if disabled users can login.

This correctly uses a URL path that includes the current organization and checks for the error message.

The previous test seems to have been a red herring.

* Minor cosmetic fixes.

* Remove needs_sync in favor of just deleting things.

* Misc review fixes.

* Ignore line length.

* Split redash.models import several modules.

* Move walrus UTC DateTimeField into redash.models.types.

* Restore distinctly loading dashboards.

* Simplify default values for user details.

* Define __repr__ methods generically.

* Consistently have underscore methods at the top of model methods.

* Fix tests.

* Split redash.models import several modules.

* Update to latest walrus and redis-py.

* Update kombu to 4.2.2 for redis-py 3.x compatibility.

* Remove redis-cli container after running Make task.

* Move buffer condition after datetime/time conditions.

* Update walrus to 0.7.1.

* Refactor some query APIs.

This uses the flask-sqlalchemy helpers consistently and makes more use of mixins.

* Post rebase fixes.

* Use correct kombu version

* Fix migration down revision

* Invitation Pending changes (getredash#3229)

* determine invitation_pending according to empty password. This commit will be reverted, I'm just deferring the implementation

* show '(Invitation Pending)' to users who haven't accepted their invitation yet

* allow resending invitations

* allow deletion of pending users from user list

* set invitation as not pending when following invite link

* prevent deleting activated users

* test that users who follow invitation links are set as non-pending invitations

* prevent re-using invitations

* invitees who use SSO will now also be marked as "non-pending"

* lint

* client: Remove estraverse (getredash#3254)

Signed-off-by: koooge <[email protected]>

* Redis based implementation of user active_at timestamp update (getredash#3256)

* Switch to simpler implementation
* Fix active_at update code
* Fix sync test

* update Flask-OAuthLib (getredash#3262)

* Fix invitation pending for existing users (getredash#3261)

* default `is_invitation_pending` to false and actively set it to true
when inviting users, so that existing users won't show "Invitation
Pending"

* fix tests that broke due to default is_invitation_pending value

* update Flask-OAuthLib

* [Data Sources] Implement Apache Drill (