Allow user to set a limit on the number of folders to be handled with

push technology.  This provide a layer of safety in case of
misconfiguration (accidentally setting too many folders to push using
classes), which can bog down the device till it is unusable.  On a G1,
25 folders is a very large load.  Fixes Issue 871.

Also, move some pending commands to the background to make way for
more important user interface activity.