added line to install django first in contributing.md

docs/topics/contributing.md

@@ -61,6 +61,7 @@ To run the tests, clone the repository, and then:
     # Setup the virtual environment
     virtualenv env
     source env/bin/activate
+    pip install django
     pip install -r requirements.txt
 
     # Run the tests

requirements.txt

@@ -6,7 +6,6 @@
 # only included the relevent sets when running tox, and ensures
 # we are only ever declaring our dependencies in one place.
 
--r requirements/requirements-necessary.txt
 -r requirements/requirements-optionals.txt
 -r requirements/requirements-testing.txt
 -r requirements/requirements-documentation.txt

requirements/requirements-necessary.txt

@@ -1 +0,0 @@
-Django>=1.8