Update to Org 8.2.7b

Update override/org-mode for older Emacs that lack
`package' (ELPA) support.

Add Org's ELPA repository to properly override the version of Org that
ships with newer (24+) versions of Emacs.
Explicitly Use org-mode for .org files

This is to support Emacs version 22 and older.  While version 22 shipped
with Org it did not add it to `auto-mode-alist'.  Even older versions
did not ship it at all.
Bind keys for find-function/library/variable*

Add drewc's find-func+ library to get `find-library-other-window'.
Install rainbow-mode from ELPA for Emacs 24.3.92.1
Fix calling `helm-descbinds' before helm is loaded
Bind `helm-M-x' to C-c M-x instead of M-x

It's load time is too slow to be called every time I hit M-x.
Fix calling `helm-descbinds' w/o helm loaded

There was a missing `require' in helm.el.  This updates my configuration
to rely upon a version of helm where I have fixed this.