soap api: set $g_project_override for all applicable mc_issue and
mc_project methods

Fixes #16028: Adding note via webservice generates wrong email content
for assigned user 

Conflicts:
	api/soap/mc_issue_api.php
New function added to retrieve bug history via API.

Fixes #9936: add history information

Signed-off-by: Laszlo Kovacs <winston01@freemail.hu>
Signed-off-by: Robert Munteanu <robert@lmn.ro>
soap api: add tests for the mc_issue_get_history call

Affects #9936: add history information
Fix #16120: Cannot modify Receive Reminder threshold
soap api: remove unused $t_lang variable ( thanks to @atrol )

Affects #9936: add history information
Fix #15196: Create history entries when creating issues with non-default
status and resolution
Add support for running complete test suite on Travis CI

Fixes #16126: Setup integration testing on Travis CI
Fix first Travis-CI build error
Travis: temporarily disable PostgreSQL builds

PostgreSQL support in master branch is known to be broken (see issue #14398) therefore it is useless to run the builds on this platform until it is fixed.
Fix #16174: Travis CI: set up PHP 5.5 build alongside 5.4
Fix #16175: Send Travis build notifications to #mantisbt-help
Revert "Fix #16175: Send Travis build notifications to #mantisbt-help"

This reverts commit 644d6a619246f9314009af08c117008373c474d9 until we reach
consensus on a notification scheme.
Travis: re-enable PostgreSQL builds but allow failures

Follow up on 02b7769e30484f639b758abc0efbea829329a0b6,
a better solution to avoid marking the whole build as failed 
due to errors on PostgreSQL, until issue #14398 is fixed.

Thanks to Rolf Kleef for the suggestion.
Fix #16202: Travis CI: set up PHP 5.3 build