[BUGFIX beta] Better error for content set on object
[BUGFIX beta] Still update HTML5 history if the previous state was null

Fixes #3195, Closes #3580
Uses document.contains to figure if element exists in the DOM

addresses issue raised in
https://github.com/Polymer/ShadowDOM/issues/365#issuecomment-33509711
[BUGFIX beta] Decode path before recognizing. Fixes #4152
Merge pull request #4263 from locks/indom-transition

Uses document.contains to figure if element exists in the DOM
Merge pull request #4362 from xtian/unicode-routes

Decode path before recognizing
Post release version bump.
Update CHANGELOG for 1.4.0 and 1.5.0-beta.1.
Merge pull request #4235 from mixonic/3195

[BUGFIX beta] Still update HTML5 history if the previous state was null
Allow 2FA for rake release:starter_kit:prepare task.
[BUGFIX beta] Ensure namespaces are cleaned up.

Prior to this change, calls to `Ember.Namespace.byName` would still
return the cached class since it was being saved off to
`Ember.Namespace.NAMESPACES_BY_ID` but not cleared.
Merge pull request #4375 from rjackson/ensure-namespaces-cannot-be-looked-up-after-destroy

[BUGFIX beta] Ensure namespaces are cleaned up.
minor doc fixes
directly return default value on get
Merge pull request #4377 from twokul/minor-fixes

minor doc fixes
Merge pull request #4378 from g13013/fix_default

directly return default value on get
[BUGFIX beta] More descriptive error when setting read-only property
Merge pull request #4381 from jayphelps/patch-1

[BUGFIX beta]  More descriptive error when setting read-only property
minor doc UI fixes
Merge pull request #4386 from twokul/minor-doc-fixes

minor doc UI fixes