Refactored calls mutex to a call goroutine
Refactored calls mutex to a call goroutine

Signed-off-by: John Zila <a51dda7c7ff50b61eaea0444371f4a6a9301e501@jzila.com>

jzila/go-framed-msgpack-rpc,keybase/go-framed-msgpack-rpc