Copy files from khan repo into a new, open-source repo.

This is not really ready for use yet: I just copied the files over
verbatim.  The only thing that changed is the file names and
locations.

Future changes will add documentation, make it so the tests
run, etc.

Test Plan:
None
Make it so the unittest runs.

Test Plan:
% tests/i18nize_templates_test.py
.......................................................
----------------------------------------------------------------------
Ran 55 tests in 0.033s

OK