SubscriptionManagerFCPTest: Test versionID during synchronzation

This is done by fixing importSynchronization() and putting it to use
again - it was unused because it was written against the obsolete
synchronization code, and thus wouldn't work against the new FCP message
layout.
SubscriptionManagerFCPTest.putSynchronization(): Optimize

HashMap.put() will return the previous entry, no need to query it twice
by a manual containsKey().
SubscriptionManagerFCPTest.importNotifications(): Remove legacy code

The function was being used to do the job of importSynchronization()
before importSynchronization() was put to use by the previous commits.
Now that its not used for that anymore, the code to handle what
importSynchronization() does can be removed from importNotifications().