Improvements to docs pages

* Add community examples page
* Clean up dependencies list
* Remove some unhelpful descriptions
* Reorganize pages
* Add migration guides page
* Fix sidebar covering footer
Publish new gh-pages with every release

* Updates the gh_pages folder so it can stand alone
* Use release-it to push to gh-pages on every release

Other small tweaks:

* Use grunt-release-it as a wrapper for release-it
* Move bower dependencies to vendor/ folder
Fix typo so we publish to correct gh-pages repo
Store row objects in _selection rather than their contents
Check that selection is not null
Resolve Ember CLI style view references.