WIP

[subhaze]

• [x] Add instructions in the README.md on what selectors to add for auto triggering the completion list (if possible, in ST3 some areas this is impossible due to how the default CSS package code is setup)
• [x] More clearly state how the plug-in works and how to add files to the cache
• [x] Look into caching linked stylesheets on file save
• [x] Add elements to the completion list in CSS files
• [x] Update font stack based on http://www.awayback.com/revised-font-stack/ and allow it to be managed via the package settings file

[subhaze]

Pushed new release out the door