Add colors and spaces when showing the method table

Following František's suggestion in https://groups.google.com/forum/#!topic/julia-dev/_5zo8o8AogQ, I've made some changes to how methods and method tables are printed.

This is how it currently looks like on OS X with iTerm and its default colors:
![colorized output](http://i.imgur.com/Xen7dn8.png "Colorized output")

Note: I've changed how parametric types are printed, but not tuples, since I tried to change the least amount of code used outside printing method tables possible.