View tree UI improvements
Add magnifying glass to inspect views on hover
View tree: add options to  show components and all views

Also added the ability to inspect a view's DOM element by clicking on its template

Done with @twokul
Show views and components in preview layer
Update tests to new features and fix bug with private view properties
Drop objects when destroyed
Better filtering of views when highlighting on hover
Accounts for view not having an element when highlighting

Fixes #65
Add name column to view tree and hide virtual views
Merge pull request #63 from tildeio/view-tree

View tree improvements
PROTOTYPE: port to firefox devtools addon
fix styles in firefox
ignore generated xpi
choose an 16x16 icon as Firefox DevTools panel icon
minor firefox css tweaks
added ff_extension_dist/data/vendor and ff_extension_dist/data/images to .gitignore
integrate Mozilla Addon SDK download and xpi generation

- add grunt-mozilla-addon-sdk to npm devDependencies
- configure new grunt tasks "mozilla-addon-sdk:download" and
  "mozilla-addon-sdk:xpi"
register build_xpi grunt task
FIX: configuring grunt-mozilla-addon-sdk to download 'firefox26' revision

needed to get a Mozilla Addon SDK version which supports chrome.manifest (http://bugzil.la/559306)
FIX: use relative image urls

relative urls on images works correctly on firefox and chrome extensions