Add selenium tests for the new layer source switching functionality on
the layer details page. Edits the values for git repository and saves
and then edits the details for directory information and saves.
Signed-off-by: Michael Wood <michael.g.wood@intel.com> Signed-off-by: Elliot Smith <elliot.smith@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>