Add ContactStatusDetail to PJSIPShowEndpoint AMI output.

Now when running PJSIPShowEndpoint, you will receive a
ContactStatusDetail for each bound contact that Asterisk
is qualifying. This information includes the URI of the
contact, current reachability, and roundtrip time.

AFS-91 #close
Reported by Mark Michelson

Review: https://reviewboard.asterisk.org/r/3797



git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@419888 f38db490-d61c-443f-a65b-d21fe96a405b