Quality of service now supports "global" parameter (default is still false)
added Channel::get() that allows one to retrieve a single message from the channel
basic.get callbacks only have to be installed for a single message, so we uninstall it right after the message was handled
empty messages could not be consumed or get, this has now been fixed
basic.get is asynchronous until the entire body has been received, only then subsequent messages are sent + first work in progress on implementing smarter buffers
fixed bug in channel.get() calls
testing - added stub to build a test based on asio