dita-ot 1.7, HEAD, devel

This adds a recipe for the DITA Open Toolkit (DITA-OT).  It provides a
formula for HEAD, 1.7, and develop (2.0-develop).

This is still broken because dita-ot wants to write into the
installation directory when it builds stuff.  Changing /basedir,
etc. helps here, but then it can't find the XML catalogs.