Adjust the js to 'find' the new style tinymce instance (Bug 1319226)

Now that we are using tinymce4
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>

Change-Id: Ie05cd22ba9c3e8d2d3573df13a6c22c0a422d873
Merge "Adjust the js to 'find' the new style tinymce instance (Bug 1319226)"