Adding a new option 'n' to app_chanspy. This option allows for the name of the spied-on

Adding a new option 'n' to app_chanspy. This option allows for the name of the spied-on
party to be spoken instead of the channel name or number.

This was accomplished by adding a new function pointer to point to a function in app_voicemail
which retrieves the name file and plays it. This makes for an easy way that applications may play
a user's name should it be necessary. app_directory, in particular, can be simplified greatly by
this change.

This change comes as a suggestion from Switchvox, which already has this feature. AST-23

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@114813 65c4cc65-6c06-0410-ace0-fbb531ad65f3