separate: remove unused Misc code

These functions were unused, and most of them are exported by the Packet
module anyways.
separate: move bit-twiddling to own Module, dedup

Lots of simple but repeated code. These same lines also appear in the
Packet module from the ocaml-packet library.
separate: remove logging module and its use
Merge pull request #44 from frenetic-lang/separate

Separate Serialization and Lwt code in OpenFlow0x04_Misc