BUG : fixed py3k compat issues

 - used xrange instead of range, but importing range from six.moves
   so should really be xrange in py2
BUG : add make_source to OpaqueFile so that it will be non-abstract
BUG : maybe fixed basic code

 - still untested
BUG : fixed naming typo
BUG : fixed un-defined variable in gray-scale case
RFCT : moved the file handling base-classes out of handler_base

This is in part to clean up code and in part to make the inheritance
diagrams sphinx generates cleaner.
DOC : re-arranged files + inheritance diagrams
DOC : more re-organization

 - all handlers modules now have pages
BLD : removed scipy build dep

There is logic in image_handler to fail gracefully if it is
not installed.
RENAME : renamed package from pyLightRafters -> pyRafters
DOC : updated the git-doc
DOC : point travis badge at correct build page
staging