[INTERNAL] fix for commit 7e5faaa6a1e9816e548f6c52b81823c69f5d403d

Lessons learned.

1. Do not ignore CI STF regression failures
2. static variables can be evil
3. Eclipse may dispose the view at any time

What actually happened:

Due to the change, the Write and Read permission actions were only
created once. When the view was disposed, the dispose methods were run.
When the view was recreated those disposed and no more functional
actions were put into the context menu.

Change-Id: Ib7052a2994b1c8f779c6c45151cc33e7f05379a2
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1669
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>
Tested-by: Jenkins CI