Recorder: Add "Delete all" to the recording list

* Deleting all recordings can be quite time consuming with the
  current single item deletion that is additionally asking you
  for each item if you are sure
* Implement a "Delete all" choice that does the job by asking
  you once and then doing the job

Change-Id: I90c78d16e37335dae517b8759a9663e1709a1997