Add basic Robot class
Add basic hello world Commander binary

This will run the command-line interface soon.
Add CLI class
Add Robot#report!
Add PLACE command to CLI
Add MOVE, LEFT, and RIGHT commands to CLI
Add Robot#move!, #turn_left!, and #turn_right!
Prefer installing gem in installation instructions

Most of the time, this gem would be installed directly on the system
where it would be used, since the binary is the main thing to have.
Update Usage section of README
Improve coverage of Robot class
Merge pull request #3 from bradfeehan/naive

Initial naive implementation