[BUGFIX beta] Prevent mandatory-setter when setter is already present.
Merge pull request #10060 from rwjblue/do-not-setup-mandatory-setter-for-props-with-setter-already-defined

[BUGFIX beta] Prevent mandatory-setter when setter is already present.
[FEATURE ember-routing-named-substates] Enable by default.
[FEATURE ember-htmlbars-inline-if-helper] Enable by default.
Merge pull request #10064 from rwjblue/enable-feature

Enable features given 'go' on 2014-12-26.
[BUGFIX beta] Remove handlebars from dependencies

It is no longer required from Ember.js.
Merge pull request #10065 from tricknotes/remove-handlebars-from-gemspec

[BUGFIX beta] Remove handlebars from dependencies
[BUGFIX beta] Use attrMorph, properties before attributes

HTMLBars is responsible for managing escaped and sanitizaition of bound
attributes. It uses an AttrMorph construct to do this. Consequently the
bind-attr and htmlbars attr syntaxes are much simpler to implement.