adds tests for word_cloud in mongo
pep8
refactor test_word_cloud, add BaseTestXmodule
adds finished test for word cloud
move BaseTestXmodule to tests.__init__
removes obsoleta word cloud test
adds word cloud integration tests to right place
pylints
revert xmodule/tests/__init__.py changes
rework word cloud tests
Word Cloud: add more tests, coverage 100%
pylint disabled W0212,W0232 for test_logic
use single test file for all world cloud tests
fix word cloud tests with `get_html`
fix BaseTestXmodule