Rename groups to be consistent with Styles TwentyXXX plugins and WordPress nomenclature.
Rename control labels

* Remove redundant "Widget" inside widget group, "Featured" inside featured group, etc.
* Remove redundant "BG" — Styles adds "Background color" next to the label
* Change "a:before" to non-technical "Before Link"
Append 'Featured Content' options to append to 2014's default 'Featured Content' group
Add Featured slider and grid prefixes
Move widgets after menus
Update readme and version
Add warning to readme
Merge pull request #1 from stylesplugin/f/setting-names

Rename options to be consistent with other TwentyXX themes.