Replace gedit with a light-weight test application

I encountered a failure of the test memory. Lots of debugging later I realised that the problem is that the test executable memory calls gedit, which I have not installed.

Relying on gedit seems a little bit heavy weight. Therefore I programmed a much simpler AT-client which triggers the necessary events/signals for the memory test.

If you reject this, then at least please document the requirements of your software. In this case that the test suite needs gedit to run properly.

Note: gedit can also be replaced by other simpler programms, like gtk-query-settings (part of GTK).