Cleans "static/" directory via Makefile
Cleans "static/" directory via Makefile

Not gitignored, and the Molecule ci scenario will generate static files
in "static/" via the collectstatic manage.py command. Running `make
clean` will now purge those files as well, to ensure a clean
environment.

freedomofpress/securethenews,freedomofpress/securethenews,freedomofpress/securethenews,freedomofpress/securethenews