Corrections so that the BGP daemon can work with the label manager properly
through a label-manager proxy. Details:
- Correction so the BGP daemon behind a proxy label manager gets the range
correctly (-I added to the BGP daemon, to set the daemon instance id)
- For the BGP case, added an asynchronous label manager connect command so
the labels get recycled in case of a BGP daemon reconnection. With this,
BGPd and LDPd would behave similarly.