Improve call forwarding reporting, especially with regards to ARI.

This patch addresses a few issues:

1) The order of Dial events have been changed when performing a call forward.
   The order has now been altered to
    1) Dial begins dialing channel A.
    2) When A forwards the call to B, we issue the dial end event to channel
       A, indicating the dial is being canceled due to a forward to B.
    3) When the call to channel B occurs, we then issue a new dial begin to
       channel B.

2) Call forwards are now reported on the calling channel, not the peer channel.

3) AMI DialEnd events have been altered to display the extension the call is
   being forwarded to when relevant.

4) You can now get the values of channel variables for channels that are not
   currently in the Stasis application. This brings the retrieval of channel
   variables more in line with the rest of channel read operations since they
   may be performed on channels not in Stasis.

ASTERISK-24134 #close
Reported by Matt Jordan

ASTERISK-24138 #close
Reported by Matt Jordan

Patches:
	forward-shenanigans.diff uploaded by Matt Jordan (License #6283)

Review: https://reviewboard.asterisk.org/r/3899



git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@420794 f38db490-d61c-443f-a65b-d21fe96a405b
Stasis: Allow internal channels directly into bridges

The patch to catch channels being shoehorned into Stasis() via external
mechanisms also happens to catch Announcer and Recorder channels
because they aren't known to be stasis-controlled channels in the usual
sense. This marks those channels as Stasis()-internal channels and
allows them directly into bridges.

Review: https://reviewboard.asterisk.org/r/3903/
........

Merged revisions 420795 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@420796 f38db490-d61c-443f-a65b-d21fe96a405b
Stasis: Use the correct return value

Return the correct value instead of always returning 0 when setting
internal status on unreal channels.

Reported by: Richard Mudgett
........

Merged revisions 420802 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@420803 f38db490-d61c-443f-a65b-d21fe96a405b
AMI/ARI: Update version to 2.5.0/1.5.0 respectively

This is to support the backwards compatible changes made in the next version
of Asterisk.
........

Merged revisions 420805 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@420808 f38db490-d61c-443f-a65b-d21fe96a405b