use new Em.Map function signatures
update testem
polyfill Ember.Map behavior
re enable beta and canary channel builds
update comments for map.js
use a for loop for ie compat and performance
don't use call, instead invoke the super function by aliasing it
Merge pull request #2326 from emberjs/update-map

use new Em.Map function signatures
Always remove the inverse record (if exists) from a belongsTo relationship
fixes #2331
Merge pull request #2336 from sly7-7/one-to-none-can-reset-value

[BUGFIX] One to none relationship unable to set a value to an old one
Fix typo in DS.Model.save in-code documetation
Merge pull request #2350 from silatham99/documentation-typo-for-ds-model-save

Fix typo in DS.Model.save in-code documetation