Parse the environment variables in Async AGI responses

[danjenkins]

Currenrty gives you

{ event: 'AsyncAGI',
privilege: 'agi,all',
subevent: 'Start',
channel: 'SIP/1000-00000005',
env: 'agi_request%3A%20async%0Aagi_channel%3A%20SIP%2F1000-00000005%0Aagi_language%3A%20en%0Aagi_type%3A%20SIP%0Aagi_uniqueid%3A%201351659241.5%0Aagi_version%3A%2011.0.0%0Aagi_callerid%3A%201000%0Aagi_calleridname%3A%201000%0Aagi_callingpres%3A%200%0Aagi_callingani2%3A%200%0Aagi_callington%3A%200%0Aagi_callingtns%3A%200%0Aagi_dnid%3A%20500%0Aagi_rdnis%3A%20unknown%0Aagi_context%3A%20default%0Aagi_extension%3A%20500%0Aagi_priority%3A%203%0Aagi_enhanced%3A%200.0%0Aagi_accountcode%3A%20%0Aagi_threadid%3A%20140372307134208%0A%0A' }

Should be able to parse these vars out