Adding subscribe method to NanoSocket.  Modifying drop to use mut self to resolve recent rustc changes.
Trimming junk with .gitignore.
Minor changes to sample nanocli
Merge branch 'master' of https://github.com/evenodder/rust-nanomsg
Minor re-organization.
Added reader/writer impls.
Merge branch 'master' of github.com:glycerine/rust-nanomsg
latest with reader and writer traits