Add sh version of flac2mp3
Fix rvm path
Add vitodo alias, greptodo function

Remove grep functionality from todo function, adding a greptodo function to
separate out the functionality. Add vitodo alias, which just runs vim on
todo.txt.
Add rbfind and rbgrep zsh functions

Add zsh functions rbfind and rbgrep. rbfind looks for filenames with a certain
pattern using the `find` command, while rbgrep looks for certain strings in the
local ruby standard library.
Clean up vim gui font configuration