[BUGFIX] Reconnect dead Asterisk streams

Replaces #152 with a fresh branch and better specs.
> Reconnect dead Asterisk ```RubyAMI::Stream```. Currently the stream remains dead upon disconnecting. This causes the client to keep trying to reconnect with a dead actor, failing continuously.
> Original issue was filed in Adhearsion https://github.com/adhearsion/adhearsion/issues/317