Fix ASIO headers "leaking" from libremote-processor headers

See [test-platform's CMakefile](https://github.com/01org/parameter-framework/blob/master/test/test-platform/CMakeLists.txt#L36): ASIO headers are "leaking" from libremote-processor because even though it should be an implementation detail, public headers of libremote-processor pull the ASIO headers.

Rework libremote-processor in order to avoid this.