fix connectNetwork corner cases

1. if we try to use the api for an already connected network
we could end up in disabling other networks since we dont
get events back in that scenario. fix to ignore connect.

2. force transition to mDisconnectingState since we expect
a disconnection when we connect to a network. If we
are in the other child states in ConnectModeState and dont
transition, we could ignore the connection/disconnection
which would cause other networks to get disabled.

Change-Id: I603d504af21c5ba09411d5e2515b8031b9f8a97a