keeps focus on the bottom of a given buffer
written by elbeardmorez copied from stackoverflow (http://stackoverflow.com/a/6341139/10771)
install by putting it in your load path, and doing a (require 'buffer-tail) in your init.el
provides the toggle-buffer-tail function to toggle the tailling of a buffer
can force it to "on" or "off"
(toggle-buffer-tail "foo.log")