DRYer coding of platform-specific coding, making django utils more util-like (vs. shared)

Conflicts:
	kalite/main/api_views.py
	kalite/main/management/commands/videodownload.py
	kalite/main/views.py
	kalite/management/commands/zip_kalite.py
	kalite/securesync/views.py
	kalite/utils/django_utils/command.py
	kalite/utils/platforms.py
Add missing portion of call_outside_command_with_output
Remove pdb, unnecessary imports
Merge pull request #634 from bcipolli/django_utils_refactor

DRYer coding of platform-specific coding, making django utils more util-like (vs. shared)
Merge branch 'release-0.10' of github.com:learningequality/ka-lite into clickable-scripts

Conflicts:
	kalite/management/commands/update.py
	kalite/utils/django_utils/command.py
	kalite/utils/platforms.py