Add a new drag behavior for block elements

Avoid the problems with the sortable, and now you can drag and drop BlockElements between cells and li elements. You can share block elements between editables and arrange the block element before or after P element in every level of nest
Merge branch 'enhance-new-drag-blocks' of git://github.com/danyg/Aloha-Editor into release-tangerang

Conflicts:
	build/dev-changelog.md
Update version for release
Make isMergeableContent() work in ie8
(cherry picked from commit 01c90b97465eff5edaa76ffb6e865177bc667868)

Conflicts:
	build/hotfix-changelog.md
Correct regular expression to check for whitespace nodes
(cherry picked from commit 2eeb7dc14ab69ea9d0cf82109e5e10259dedfbdd)

Conflicts:
	build/hotfix-changelog.md
Merge branch 'hotfix' of github.com:alohaeditor/Aloha-Editor into release-tangerang
Prepare release.
[maven-release-plugin] prepare release alohaeditor-0.23.19-commercial
[maven-release-plugin] prepare for next development iteration
Prevent dropping of blocks within themselves or within UI regions
Restore selection and scroll position after drop in IE
[maven-release-plugin] prepare release alohaeditor-0.23.20
[maven-release-plugin] prepare for next development iteration
Merge branch 'hotfix-tangerang' of github.com:alohaeditor/Aloha-Editor into release-tangerang

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

Conflicts:
	build/hotfix-changelog.md
	pom.xml
Prepare changelog
[maven-release-plugin] prepare release alohaeditor-0.24.0-commercial
[maven-release-plugin] prepare for next development iteration
Blockmanager: Fixed scripts in blocks being executed
Remove obsolete Firefox workaround