Adjusting places where form error message's container appears escaped

Bug #1379060

Looks only to be a problem with $form->set_error() and block config
forms.

Change-Id: I8ac8a7c96446e1dd37a312f482f4d31ad46dae3d
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
Merge "Adjusting places where form error message's container appears escaped"