Fix subscription ID & unsubscribe

Previously, the subscription ID was set to the *length* of the subscriptions
hash.

This leads to instability in the presence of Unsubscribe where distinct subscriptions separated
by unsubscriptions can end up being given the same subscription ID
fix the fake
Merge pull request #10 from cloudfoundry/fix-unsubscribe

Fix unsubscribe
WhenPublishing/Subscribing take callback/message

Signed-off-by: Max Brunsfeld <mbrunsfeld@pivotallabs.com>
Add a timeout to the Nats Dial.  Eliminates long connect hang times.