test: workgroups.feature: add more sleeps and other hacks

- also revert a while added in e7695fa3ee519b3e72c79666114a3aa4db5cfaee.
test: workgroups.feature: try stroking the modals gently with js

also run that 1 buggy test in jsbrowser…
Admin mode: admin can delete a media entry

Squashed commit of the following:

commit 0b07a370bd239da9501988186d66440412bd86c1
Author: Michał Podlecki <m.podlecki@op.pl>
Date:   Tue Oct 7 11:12:27 2014 +0200