Memory Leaks

[sheldonth]

Correct the misuse of dynamically allocated C++ memory so that using the uv_asyc() callback API doesn't leak the pointer data being passed through.

[sheldonth]

Best idea is to use unique_ptr on every MessageStruct so that once so that the effect of reassigning handle->data to Null is that it's uniqueness count goes to zero and it is cleaned up and we stop leaking huge char arrays.