address some reentry issues

dont bother ourselves with binding to the service,
just request the work/status and it will bind automatically

hide from recents. we cant have people killing our service

singletask cant use onSavedInstanceState so put a global
mBeamInProgress to decide what to do when coming back

if we left via back button we cant even use mBeamInProgress
so check if service is running to decide

change service to keep running if backgrounded and have
activity request shutdown

Change-Id: I03b57b32079c10eb5cb6c0a3f389284db251fa44
cleanup the p2p disconnect

Change-Id: Id5aa5b1e60a430db6582b94b6450551d011695b6
WifiDirectManager: do some cleanup add doc

Change-Id: Ic221c7d09d0188c1bdfd7ec0444fe58295285318
fix possible npe

Change-Id: Ie0a781fcfec88cf4ff1cca954ef25e6a5694911e
fix typo in license

Change-Id: I0c9d152b1b3dc43179b5076a16c5526850168c7a