Added a new lightweight-dom module. See documentation in js file for
details.
Added basic tests for this dom.
Checkin of the new lightweight-dom.
Per discussion with Pavel, changed tabCount on node to reflect current
cursor position for non-structural (empty/comment) nodes.
Merge branch 'master' into bugs/no-shelf-elements-for-children-of-alias-nodes-61664576
Final touches to lightweight DOM to support actual fix to pivotal
bug 61664576.
Updated app/index.html to add a reference to lightweight-dom which
is now being used by raml-hint.
Merge branch 'master' into bugs/no-shelf-elements-for-children-of-alias-nodes-61664576

Conflicts:
	app/scripts/app.js
Added some more test cases for short-circuiting the shelf when
a reference node is in the parent path.
Minor formatting changes in response to code review
Merge branch 'master' into bugs/no-shelf-elements-for-children-of-alias-nodes-61664576
Merge branch 'master' into bugs/no-shelf-elements-for-children-of-alias-nodes-61664576