Add thumbs to edxapp venv so XBlock workbench will work.
Merge pull request #511 from edx/brian/add-thumbs-to-datajam

Add thumbs to edxapp venv so XBlock workbench will work.
Add dependencies needed for matplotlib.
Update edx-workbench script to correctly find templates
Merge pull request #513 from edx/brian/add-matplotlib-deps

Add dependencies needed for matplotlib.
Merge pull request #514 from edx/rocha/fix-workbench-script

Update edx-workbench script to correctly find templates
datajam: remove virtualenv requirement
Merge pull request #515 from mulby/gabe/datajam/dont-require-venv

datajam: remove virtualenv requirement