Added bandwidth generation method

Added few methods in compute linux client to generate
bandwidth from server to client. Also, some md5sum related methods and
extracting network bytes from server
* Fixed some issues with generate_bandwidth_from_server_to_client method
* Removed do_bandwidth_server_to_client from server behavior
* Changed download_a_file() to retrieve_file_from() method
* Replaced md5sum method with a common tool method

Change-Id: Ib28acbf81a19631ca176ea6cfefd19a0a8ff6738
Merge "Added bandwidth generation method"