Partial pick of Evernote's evernote/pootle@2f453d22

These changes might be required by the following picks.

The rest of the changes in that commit are either necessary or where later
dropped or changed at Evernote.
Make #footer stick to bottom

Conflicts:
	pootle/templates/layout.html
Make #footer stick to bottom
Fix footer overlapping with the content on tall pages

Conflicts:
	pootle/static/css/style.css
Partial pick: Added 'Terms and Conditions' links to the footer

Pick note: Only picked the CSS styles.

Conflicts:
	pootle/templates/layout.html
Added delete method to <Directory> (fixed http://bugs.locamotion.org/show_bug.cgi?id=2776)

Conflicts:
	pootle/apps/pootle_app/models/directory.py
Used iterator to avoid filling the internal queryset cache