app_page and app_confbridge: Fix custom announcement on entering conference.

The Page and ConfBridge custom announcement did not play when users
entered the conference.

* Fix the CONFBRIDGE(user,announcement) file not getting played.  The code
to do this got removed accidentally when the ConfBridge code was
restructured to be more state machine like.

* Fixed play_prompt_to_user() doxygen comments.

* Fixed the Page A(x) and n options for the caller.  The caller never
played the announcement file and totally ignored the n option.  The code
to do this was lost when the application was converted to use ConfBridge.

* Factored out setup_profile_bridge(), setup_profile_paged(), and
setup_profile_caller() routines to setup ConfBridge profiles.  Made each
profile setup routine use the default template if one has not already been
setup by dialplan.

(closes issue ASTERISK-20990)
Reported by: Jeremy Kister
Tested by: rmudgett
........

Merged revisions 380894 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@380896 f38db490-d61c-443f-a65b-d21fe96a405b