LUN-1258: folders and files are now restorable
Merge branch 'master_pbs' into LUN-1258
LUN-1258: restore functionality for files/folders now available
* fix: when restoring folder, its files were not restored
LUN-1258: fixed infinite loop when restoring file
* added tests for file restoring
* SettingsOverride can now be used as function/class decorator
LUN-1258: added folder restore tests
* changed messages and method names a bit to be more explicit
* fix: don't allow user to submit restore multiple times.
Merge remote-tracking branch 'origin/master_pbs' into LUN-1258

Conflicts:
	filer/tests/models.py
Merge pull request #39 from pbs/LUN-1258

LUN-1258: restore deleted files and folders