Replace eval-after-load with with-eval-after-load

Previously I was using "eval-after-load" to do configuration only after
some Emacs package is loaded. Emacs 24 defines the macro
"with-eval-after-load" which is better then "eval-after-load".

See
http://stackoverflow.com/questions/21880139/what-is-with-eval-after-load-in-emacs-lisp