Fix persistent tasks and expand scope

- Fixed missing tag closure on the xml for storing Intent categories.
- Shortened timeout for flushing tasks to persistent storage from
one minute to ten seconds.
- Made persistency the default except for those tasks on the home
stack and those tasks that exclude themselves from the recent task
list.
- Fixed deletion of tasks after restoring. Tasks now survive a second
reboot, not just the first reboot.
- Fixed sort order so most recent tasks will be restored at front.

Fixes bug 15672002.

Change-Id: I16d87d58c6fd2e879cfd0c0b18b2694432a79b71