Add tnoda/enable-show-trailing-whitespaces.

It is created on ad hoc basis.
Show trailing whitespaces in clojure-mode.
Update the install script for org-mode to download the latest stable 7.9.3a.
Do not require org-install.

org-install is obsolete as of 7.9.3a.
Merge branch 'org-mode-7.9.3a'