Resolves provide-skin issues
Updates provide-theme to work like provide-skin
Updates default skins and themes to be relative so they can be completed by adjust-path
removes excess whitespace
Merge branch 'master' of github.com:LightTable/LightTable into feature/provide-custom-styles
Makes skin update on inject like themes, allows multiple skins
Only applies CSS for the current skin
Removes old commented code
Merge pull request #990 from joshuafcole/feature/provide-custom-styles

Fixes provide-skin and provide-theme for custom CSS.