add integration tests for switching languages
fail fast on database errors
create tests for switching languages
remove redundant integration_tests.py
solve #2016: convert set_user_language to POST data instead of GET
remove unneeded html attributes
implement hack to update csrf token
move i18n testing utility functions to its own mixin subclass
setup a client in I18nTestCase
add test language pack zips and logging statement for langpack download url
move delete_language command from updates.__init__ to i18n.__init__
mock the download of language packs to download local test zip files instead
make updatesframework.display_notes use logging framework instead of directly writing to stdout
silence logs when installing/uninstalling language packs when running tests
dont test deutsche for now
Merge branch 'release-0.12.0' into 2016
move language installation logic to I18nTestCase
make i18nTestCase a pure mixin class
move uninstalling of a language to i18nTestCase too
cleanup based on review