Add .nrepl-port to .gitignore
Break out components of the command map

This allows more freedom for the implementation to process the
command map.  Require for proper environment forwarding.
Updated project.clj, release notes and readme for 0.5.0
Merge branch 'release/0.5.0'
Merge tag 'ssh-transport-0.5.0' into develop

ssh-transport-0.5.0
Updated version for next release cycle