Adds the ability to move a page under a page with no children

I switched to using the jQuery nestedSortable plugin instead of the
sortable plugin provided by jQuery UI, because Pages actually being in a
tree structure, they need a tree editor.  This commit temporarily breaks
some functionality such as remembering which pages were open and closed.
fixed pagetree hiding of subpages
Fix pep8 fail (lines too long)
Use the decorator syntax for decorator
Added Dominican Python to sites in README.
Provide Mezzanine's settings object to the COMPRESS_OFFLINE_CONTEXT setting for django-compressor. Closes #505.
pep8 fix and some comments.
Fix the bugs that we had with nestedSortable
only .nestedSortable() the first ol
Fix front-end editing links for elements not positioned relative to the document. Use visibility hidden and jquery offset function to ensure edit links are always positioned relative to the document and not relative to a positioned ancestor.
Merge
Clean up the new page sorting view.
Added Rocky Meza to AUTHORS
Added stackful.io to sites in README.
Merge
Merge
Remove old hack for initial page tree click bug that no longer exists. Closes #509.
Fix null handling in page sorting view.
Merge
Added Jonathan Potter to AUTHORS