Fix crash in PresenceState AMI action when specifying an invalid provider

This patch fixes a crash in Asterisk that could be caused by using the
PresenceState AMI action while providing an invalid provider. This patch
also adds some additional warnings when a user attempts to provide the
PresenceState action with invalid data, and removes some NOTICE statements
that were still lurking in the code from testing.

(closes issue AST-1084)
Reported by: John Bigelow
Tested by: John Bigelow


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@381594 f38db490-d61c-443f-a65b-d21fe96a405b