manager: ExtensionStatus event status human readable

manager: ExtensionStatus event status human readable

When an 'ExtensionStatus' event was raised it included the status as a
numerical value, but did not include a text description of the status.
Added a 'StatusText' field to the event which is a string representation
of the extension status.  Also added this to the 'Extension State' command
response.

(closes issue ASTERISK-23154)
Reported by: Jonathan Rose

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@406647 65c4cc65-6c06-0410-ace0-fbb531ad65f3