Add first pass on editor layout

- Moves require config into own JS to avoid async issues when trying to
use plugins when consumed the editor
- Renames default.spec to editor.spec and adds new tests
- Update fixtures
- Allows plugins
- Includes more default dependencies (scribe, marked, to-markdown…)
Add sticky toolbar plugin
Include source converter
Tidy up source converter formatting
Create wrapper for Scribe
Use strict mode
Update tabbing
Remove keyboard shortcuts for unsupported commands
Add some basic styling to example
Remove sticky toolbar references from Editor class

And add basic styles for sticky toolbar
Allow additional options params in sticky toolbar plugin
Add shim for he
Move sticky plugin toolbar
Add all dependencies to karma test rig
Remove he shim, instead make he a dependency of to-markdown
Add he dependency to karma test rig
Refactor to add setup and teardown
Add jsdoc
Add some jsdocs documentation
Add shims for Phantom JS' lack of bind and mutation observer API support