Remove the install section of packages related to clojure-mode.
Install clojure-mode using el-get.
Replace nrepl.el with CIDER.
Install ac-nrepl using el-get.
Remove nrepl-ritz.

nrepl-ritz has not supported CIDER so far.
Rename tnoda/cider-mode-hook with tnoda/cider-repl-mode-hook.
Move ac-nrepl-setup from nrepl-*-hook to cider-*-hook.
Merge branch 'nrepl-el-to-cider-migration'