MDL-47975 assign: Stop gap fix for random time fails.
MDL-30968 mod/forum Fixed group link
MDL-47502 test_statslib_cron_daily: fix provider

Fiddling with the database in the data provider causes "out of sync"
errors when running suite tests.
MDL-47391 Update pagelayout for default profile configuration for MOODLE_27_STABLE
MDL-39692 grade: Ability to delete letter boundary
MDL-39692 grade: Little code clean up of letter boundary deletion
MDL-39376 enrol: Optimized setting for ldap and database
MDL-48093 HTML 5 video: Firefox now supports .mp4
Merge branch 'MDL-48093-m27' of https://github.com/sammarshallou/moodle into MOODLE_27_STABLE
Merge branch 'MDL-47975-27' of git://github.com/damyon/moodle into MOODLE_27_STABLE
Merge branch 'MDL-47502' of https://github.com/eugeneventer/moodle-fixes into MOODLE_27_STABLE
MDL-47502 statslib tests: improve test

While integrating I noticed some problems which already existed in this
test:
* The enrolment data generator was not used
* The student roleid was hardocded
* The role assignment was at site level..
Merge branch 'MDL-30968-m27-forum-group-link' of https://github.com/amandadoughty/moodle into MOODLE_27_STABLE
Merge branch 'MDL-39692-27' of git://github.com/FMCorz/moodle into MOODLE_27_STABLE
Merge branch 'MDL-47391_M27' of github.com:ninelanterns/moodle into MOODLE_27_STABLE
MDL-30968 mod_forum: No picture link to group when no groups mode
weekly release 2.7.3+
MDL-47832 cache: data source aggregation fixes

The data source aggregate feature (which is advanced) has been
very broken for several releases.
As it still has potential use cases we decided to keep it instead
or getting rid of it.
The changes made here include:

* Getting data source aggregates working.
* Better commenting about data source aggregates.
* Consistent naming of args and variables.
* Unit tests to cover its expected operation.