Added further upstream updates
update Gemfile.lock to latest sass version 3.2.5
build bootstrap v2.3.0 from SASS files
generate bootstrap form sass files
update javascript files to v2.3.1
update docs to v2.3.1
Merged in 7a29798d98
update built css files and documentation
customize composer.json
Mixin file update
Merged in c36f81cb9d1fa
Reapplied fixes to mixins file