Check that start button works after pressing stop button.

[goldarte]

The bug description
There's been report that animation doen't restart after pressing stop button and the user has to restart clever-show service manually.

Steps to reproduce the behavior

1. Press stop
2. Move copter to start position
3. Press start
4. Nothing happens

Expected behavior
Animation should start when start button is pressed after stop button was pressed

Version
v0.3-alpha.5

[goldarte]

I corrected logic of tasking manager (ed67599) and also I change behavior of the stop button to stop and land (d3a8d11), because I don't think that user needs to fully stop animation with hovering copter. The user can pause animation and do what he want or he can fully stop animation that continues with copter landing, so we don't need separate stop button I think.