Add name argument to BridgeWait() so multiple holding bridges may be used

Changes arguments for BridgeWait from BridgeWait(role, options) to
BridgeWait(bridge_name, role, options). Now multiple holding bridges may
be created and referenced by this application.

(closes issue ASTERISK-21922)
Reported by: Matt Jordan
Review: https://reviewboard.asterisk.org/r/2642/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@395509 f38db490-d61c-443f-a65b-d21fe96a405b