Bash completion

Bash completion script for tab completing main module commands and package names for `#install` and `#uninstall` commands.

Added a pseudo-private `#_listallpackages` command to the main executable in order to get the package names out of ruby land easily. There's probably a much better way to do this.

You can use this script by sourcing or copying the `contrib/bash-completion.sh` file to `$(brew --prefix)/etc/bash_completion.d/kmc`.

![screen shot 2014-08-06 at 10 12 14 pm](https://cloud.githubusercontent.com/assets/297461/3836602/4441e004-1dd8-11e4-9785-5f93b91ae01c.png)