add the CreateTeacherMixin
in the browser: fix the selecting of the facility when logging in
disable facility deletion UI for teachers
Disable "Delete Group" button for teachers
disable coach deletion button for teachers
load i18n exercises into the app's static dir
Merge pull request #2171 from aronasorman/2165

load i18n exercises into the app's static dir
fix the start of downloading of language packs
Merge pull request #2166 from aronasorman/2158

Disable some deletion features for teachers
Fix by_zone bug on Device, introduced with soft_delete/all_objects.
Merge branch 'release-0.12.0' into nalanda-rct2

Conflicts:
	kalite/testing/mixins/facility_mixins.py