Reduce the sync window from 20 items to 5 (partial fix #2149029)

* This change trades off network time / overhead with time keeping
  ContactsProvider2 busy
* The net effect will probably be to reduce some UI slowdowns while
  syncing Exchange contacts, while increasing the time it takes to
  sync those contacts

Change-Id: I56e2358698aa4c901cda4559f7a8f9117681f627
1 file changed