Merge remote-tracking branch 'upstream/release-0.11' into hotfix_video_counts

Conflicts:
	kalite/main/views.py
	kalite/version.py
Merge pull request #877 from jamalex/hotfix_video_counts

Fix video count bug and re-enable default caching
Enable Postmask in "test mode" by default for central server.
Allow Postmark settings to be overridden properly in local settings.
add m2crypto installation
add psutil install
Have postmark sender default to CENTRAL_FROM_EMAIL.
Fix: Swapping order of dest and src path in enumerating files to zip.
Merge pull request #882 from gimick/optimizepi_psutil

Add psutil to optimizer pi + cherrypick m2crypto install
a few fixups
Merge pull request #881 from jamalex/postmark_test_mode

Added default settings for Postmark, to have it automatically use test mode rather than failing
Properly set permissions on executable scripts during zipping.
Add newlines to generated install_from_zip commands to avoid errors.
Corrected CC link/image to CC-BY-NC-SA 3.0
Merge pull request #885 from jamalex/fix_installer_zipping

A few fixes to get zipped installer working correctly
Move file
Update file to loop through all locale paths, and skip directories that don't exist.
Merge branch 'release-0.11' of github.com:learningequality/ka-lite into develop

Conflicts:
	scripts/optimizerpi.sh
Merge branch 'develop' of github.com:learningequality/ka-lite into missing-locale
Fix ensure_dir: check that path is actually a directory path