Fix ls alias color issue

Prior to this commit, ls colors were not properly displaying on linux
mint 15 Xfce. The problem was it was it was using my Mac OSX ls alias,
`ls -GF` for ls, which DOES add color in OSX but that's because OSX is
behind on which version of ls it uses (great!). This commit removes that
alias and uses the up to date ls program that comes with linux mint 15.