Account for document.body being absent.
Merge pull request #72 from eventualbuddha/account-for-null-document-body

Account for document.body being absent.
Everything goes through an adapter

- Port is now environment agnostic because it uses the adapter
- Created BasicAdapter and ChromeAdapter
- Renamed extension_dist to dist_chrome and ignored generated files

For every environment you will need two adapters.
One for the ember inspector and one for EmberDebug.

Ember Inspector:

```javascript
var EmberExtension = App.create({
  adapter: 'chrome'
});
```

Ember Debug:

You can pass the adapter name when injecting:

```javascript
chrome.devtools.inspectedWindow.eval('(function(adapter) { ' + xhr.responseText + ' }("chrome"));');
```
PROTOTYPE: port to firefox devtools addon
fix styles in firefox
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
FIX: tweaks on the ember inspector panel initialization

- reload attached tab on initialization (fix ember not detected if tab
  is already loaded)
- remove custom messages used during ember devtool panel on Firefox
minor cleanups on ember-inspector firefox devtool panel
FIX: DOM inspection requests ported to Firefox Devtool panel
fix exceptions on missing document.body and reloading devtool panel
move app port initializer into port.js
various css fixes: fix image url and table tree flex box and split alignment
cleanup firefox extension code

- move devtool panel code in a jetpack module
- clean up devtool panel code
- use jetpack workers to attach target tab and devtool iframe
- reduce logging
updated grunt-mozilla-addon-sdk dependency and task options