i18n of common/lib/capa/capa files

Also pep8, pylint, and style fixes
Covers:
{capa_problem, correctmap, customerender,
inputtypes, responsetypes, util, xqueue_interface}.py
LMS-1744

Conflicts:
	common/lib/capa/capa/capa_problem.py
	common/lib/capa/capa/responsetypes.py
	common/lib/capa/capa/util.py
	common/lib/xmodule/xmodule/capa_module.py