adhearsion does not know how to parse agi_xxx: param without value

call.rb contain a method called separate_line_into_key_value_pair.
This class method uses regex in order to parse the agi_xxxxx params from Asterisk, but it does not know how to handle parameters with no values like so:

"agi_accountcode:"

I'm attaching a patch of the parsing in order to also be able to handle such case.