Move twitter theme into root folder.

Themes are no longer namespaced into a themes folder.
Update widget API

Widget config now goes into config.yml.
Add config settings/docs for asset pipeline.
Update pages to _root folder.
Drop file extensions in navigation ids.
Update layout to new _root collection.
paginator layout now works for any collection.
layouts now need to be named after the collection exactly to be used as default.
Add author data to posts if available.
Drop bottom padding from layout.
Update config.yml to ruhoh 2.1
Update readme to 2.1
Update gem source to more secure version.
Add notes to Gemfile to enable asset pipeline.
Check in Gemfile.lock.
Use ruhoh from rubygems and add Gemfile.lock.
Release v2.1
Upgrade to ruhoh 2.1