res_parking: Add Parking manager action to the new parking system

(closes issue ASTERISK-21641)
Reported by: Matt Jordan
Review: https://reviewboard.asterisk.org/r/2573/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@392915 f38db490-d61c-443f-a65b-d21fe96a405b