Copies stumble logs into the sdcard instead of deleting them

This is an incomplete patch for #1255, but I just wanted some code that merges cleanly.

This *mostly* works, except that there is a set of logs that are stored only in memory.  Whenever the save logs to disk flag is enabled, we must flush those memory buffers to disk, then do the regular upload thing.
I've removed the deleteAll() code in the ClientDataStorageManager.  The base DataStorageManager also doesn't try to call the single file delete() method anymore so no attempt will be made to move the files into the sdcard.

Added some comments that deleteAll() is a special case.

Changes are in : 35c3da45ee31959d27f72002de417fd180671f72