New use(r)-package based configuration

The var `my:disabled-packages` gives control on what features are ought
to be installed and configured or not.
Merge branch 'user-package'
Add leiningen to requirements list (thanks @jos3ma)
Update README.org
More fixes to README
nrepl is dead, long live to cider.
Enable paredit everywhere.
Double rainbow all the way up to the parens
Replace paredit with smartparens
Defer emms loading
Use new color theme: cyberpunk
Added rainbow mode
Added clj-refactor
Added clojure-test-mode
Order ace-jump-mode-submode-list by granularity

This puts ace-jump-char-mode first, which is what I use the most.
Add cider-tracing
Fix package disable

This fix applies to both package.el and el-get packages.
Add note about byte-compile and disabling packages
Use melpa for emms-media-info, jquery-doc and rcirc-groups

Another step towards droping el-get completely.
zencoding: leave C-j alone