Merge pull request #615 from FortnoxAB/patch-4

Interval instead of timer for the idleConnectionCleanup so that it keep cleaning up. Add retry so that a failure during cleanup will not stop future cleanups

Merge pull request #615 from FortnoxAB/patch-4

Interval instead of timer for the idleConnectionCleanup so that it keep cleaning up. Add retry so that a failure during cleanup will not stop future cleanups

Merge pull request #614 from FortnoxAB/patch-5

Closing connection instead of just creating observable that is not subscribed to

Merge pull request #613 from FortnoxAB/patch-3

Fix sometimes empty response.

Refactor spectator metrics

__Problem__

Currently the listener does not expose metrics to specific events but instead does internal calculations and expose custom gauges. This is limiting as it gives less information.

__Modification__

Modified the metrics to represent the actual events.

__Result__

More flexible insights.

`RequestN` reduces with completed subscribers.

#### Problem

Re-calculation of max `requestN` per subscriber did not take into account removed subscribers correctly. This causes the `requestN` value to decrease over time when subscribers are completed.

#### Modification

- Modified `recalculateMaxPerSubscriber` to take old and new subscriber count instead of trying to determine the correct value from the current subscriber queue size.
- `subscribers.remove()` does not happen on unsubscribe but only from the task that recalculates the max `requestN` values. This also coalesces multiple removes into a single task run.

#### Result

Consistent `requestN` values with new subscribes and completions.

Escape html special characters in default error response generator.

Upgrade netty to 4.1.5.Final (#547)

Upgrade netty to 4.1.5-Final (#546)