[bug 1042560] Remove unused packages in dev VM

This adds a command to the VM provisioning script which removes
unused packages after provisioning is done and hence frees up some
space on the virtual machine.
Merge pull request #325 from lgp171188/1042560-remove-unused-packages

[bug 1042560] Remove unused packages in dev VM
Update django-mozilla-product-details

This updates to a version that doesn't import product_details from
setup.py.
Update product details

Figured while I was updating the django module, I might as well update
all the data, too.