Tidy tests runner code (code is a bit less ugly now).

Did not actually solve the bug I wanted to solve though.
Better error messages. Fix the "empty error message" bug.
Stopping tests now mark scheduled tests as "not started".
Add two log lines for easier debugging..
Do not update_status when it is not desired.

Fix run tests button not having the proper state after changing the
current dropdown menu item while tests are running.
Correct two typos in docs.
Merge remote-tracking branch 'origin/topic/bf_fix_tests_runner' into develop

* origin/topic/bf_fix_tests_runner:
  Do not update_status when it is not desired.
  Add two log lines for easier debugging..
  Stopping tests now mark scheduled tests as "not started".
  Better error messages. Fix the "empty error message" bug.
  Tidy tests runner code (code is a bit less ugly now).
Merge remote-tracking branch 'origin/topic/bf_typos' into develop

* origin/topic/bf_typos:
  Correct two typos in docs.