make solarized and vimdiff useful

git-svn-id: https://svn.sixfeetup.com/svn/private/claytron/dotfiles/trunk@47340 7abc7aa1-7e52-db11-9331-00508bd72530
only use signify for particular version control systems

git-svn-id: https://svn.sixfeetup.com/svn/private/claytron/dotfiles/trunk@47341 7abc7aa1-7e52-db11-9331-00508bd72530