Remove circular dependency

This ciruclar dependency had caused TableCell to be `undefined` in
table-selection.js
Correct jQuery to $
Correct regular expression to check for whitespace nodes
Make isMergeableContent() work in ie8
Merge branch 'hotfix' of github.com:alohaeditor/Aloha-Editor into release

Conflicts:
	build/hotfix-changelog.md
Merge branch 'release' of github.com:alohaeditor/Aloha-Editor into release