Don't rely on :selected, makes Select2 compatible with jQuery builds without Sizzle.
Merge pull request #1795 from arendjr/master

Don't rely on :selected, makes Select2 compatible with jQuery builds without Sizzle
Fixing reference to undefined this triggering change on multiselect
Merge pull request #1801 from bobbyrenwick/patch-1

Fixing reference to undefined this triggering change on multiselect
#1807 add support for MutationObserver

Better support mutation events in Firefox
Merge pull request #1808 from cmcnulty/#1807-Mutation-Observer

#1807 add support for MutationObserver
Modified syncCssClasses to use output of adapter when applying a class rather than applying the original class
Merge pull request #1819 from jrlynchii/master

Modified syncCssClasses to use output of adapter when applying classes.