Drop spurious var set statements
Bring back deprecated initializers

Libraries such as ic-ajax are dependent on the old initializers in
ember-data (such as "store"). This brings them back temporarially, but
they will eventually be removed and are non-functional.
Update changelog for initializer and container setup changes
Merge pull request #1867 from mixonic/cleanup-initializers

Cleanup initializers
Import InvalidError instead of looking at global DS
Merge pull request #1891 from Kerrick/remove-reliance-on-global-ds

Import InvalidError instead of looking at global DS