rip --auto-ripenv and rip-find-package

[cldwalker]

Branch

In a multi-ripenv workflow I've found it handy to have package-centered commands work automatically regardless of the current ripenv. This option does that by finding the package's correct ripenv and setting it. I realize --ripenv exists but this is less typing and would make it easier to use rip's packages in a simpler, global manner.

Examples of commands that would benefit from this:

$ rip -a uninstall ronn
$ rip -a info ronn
$ rip -a readme ronn

# Plugins
$ rip -a open ronn
# From http://github.com/cldwalker/rip-licious
$ rip -a test ronn
$ rip -a git log ronn

Notice I've also added rip-find-package which completes the TODO in rip-uninstall. I can refactor that part and add tests as needed.