Clearing the tinymce editor after feedback submitted (Bug #1321972)

Instead of trying to clear the textarea of content we just clear the
active tinymce of content.

Change-Id: I59bfc9b7f8dc41e94a801ff27f5d3f92395347df
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
Merge "Clearing the tinymce editor after feedback submitted (Bug #1321972)" into 1.9_STABLE