Eric Schulte writes:
> See http://orgmode.org/manual/Languages.html for the documentation on
> how to activate and disable org-babel languages.

That actually produces the error:

File mode specification error: (void-variable org-babel-tangle-lang-exts)

as the OP has found out (and I can reproduce it).

The reason is that none of the ob-<lang>.el files do a (require
ob-tangle), but try to change a defcustom in ob.tangle.el that is only
declared, but not yet available at the time.  I've quickfixed it by
moving the require for ob-tangle in org.el to the beginning of the file,
but this is now relying on the fact that org is implicitly loaded for
getting the major mode set up, so all the babel language files still
need to be cleaned up.