Try to work around the "ping loop" problem in some Exchange 2003 servers

* First try reloading the folder list; this can sometimes work
* Otherwise, change push to 5 minute sync
* Send notification if we switch to 5 minute sync so there are no surprises
* Added syncStatus column to EmailProvider (can be used for any purpose)
* Use syncStatus to keep track of sync type, result type, and change count;
  detect ping loop as consecutive ping's with no changes
* Remove InteractiveSyncService (no longer needed)
10 files changed