Added tag_cloud as a custom aside, and added instructions to README to i...

Hey ! 

I am using your oscailte theme for my personal website.
I added tagcloud plugin by https://github.com/tokkonopapa/octopress-tagcloud to your theme for my use.
I forked and made the necessary changes to your theme and added an instruction to your README file.
Accept this pull request if you find this useful.

P.S - This is my first fork-pull on github, Let me know if there is anything I can do better.