This just deletes all the upgrade steps previous to 2.7.0. Some
small adjustments, like adding missing MOODLE_INTERNAL or tweaking
globals can also be applied when needed.
Next commit will get rid of/deprecate all the upgradelib functions
not used anymore in codebase.
version = planned 2015051100 release version
requires= current 2015050500 rc1 version
Note: On purpose, the course format social wrong version (2015102100)
has been kept unmodified. Looking forward a solution right now.
Better performance, more reliable, completely self contained,
more validation and full backwards compatibility.
This will also allow us to implement ignoring of plugins.