added send_to_human method to EchoLayer to encapsulate some yowsup code, renamed Client to StackClient to highlight the relationship between Client and the stack it initialises, added send_to_stack method to StackClient which uses the stack loop, implemented handle_outbound_message method using the above method(s)
added send_to_human method to EchoLayer to encapsulate some yowsup code, renamed Client to StackClient to highlight the relationship between Client and the stack it initialises, added send_to_stack method to StackClient which uses the stack loop, implemented handle_outbound_message method using the above method(s)

praekelt/vumi-yowsup,praekelt/vumi-yowsup