Implement task to retrieve server status

It might happen that the Android application gets shut down, but if the
server endpoint is still running the motion detection the Android
application should reflect that after it is newly started. For that
reason the server status can be retrieved.

I have added a new asynchronous task which requests the status and acts
accordingly. Also I have added an example settings file which is not on
gitignore and which should be modified by the user.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Refactor package structure

Finally, I have deleted the last legacy files from the prototype. I
should have made branch in the first place to avoid this mess. All files
are now placed in the securitas package. Hence, I have fixed some import
statements.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Improve smoothness of the Android frontend

There is still some unpleasant behavior in certain situations. I have
minimized this by dealing with these cases. This was mostly done by
reordering statements. Even though it works now better I would prefer to
specify something like a state machine after which the client behaves to
avoid such situations all together.

Also I have changed the layout from LinearLayout to RelativeLayout
allowing me to place the progress bar and the view for the snapshot in
the same place. The status request task is now used in the onCreate()
method.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>