Add security definer and search_path to event trigger functions.

Similar to pgaudit#156, this prevents users from defining their own versions of functions used in the event triggers. Either one should be sufficient on its own, but both provides better defense against regressions.

Increase version number to separate from mainline releases

Stamp 1.3.2.

Add SET to documented list of commands in the MISC class.

Update master to PostgreSQL 10.

Bump 9.5 extension version to 1.0.6.

The 9.5 version of the extension was accidentally left at 1.0 which does not reflect the various updates. The default is now set to 1.0.6 and an empty update script is included. Run:

alter extension pgaudit update to '1.0.6'

to update the extension version to 1.0.6, though there are no apparent problems with leaving it at 1.0.

Added environment vars to Vagrantfile to reduce deltas between branches.