Adds platform.connecting property.
Adds platform.connecting property.

This hopefully helps clients avoid race conditions in which isConnected()
is called while connect() is underway, and then resolves to false at about
the same time as connect() succeeds.

This change also removes the check for whether the object is already connected
before attempting to connect. connect() now will always attempt to connect,
and thus the 'connect' event will always fire upon success.

hlapp/wirelesstags-js