Moved groundwork sub-directory's content to Groundwork's main directory.

* Fixed error when updating Groundwork via Update Manager. Before in
  sites/all/themes, the structure was:

  groundwork/groundwork/groundwork.info
  groundwork/subwork/subwork.info

  After this commit, the file structure is:

  groundwork/groundwork.info
  groundwork/subwork/subwork.info

Note: See CHANGELOG.txt for  more details.