Don't create wheels for dependencies but store offline:

Previously we used AWS which meant that we could create wheels
from our requirements and then install them offline which made
deployments quicker.

We're no longer using AWS so let's remove that.

Although CloudFoundry supports installing dependencies in an offline
environment as documented here:
http://docs.cloudfoundry.org/buildpacks/python/#vendoring

To achieve this we create a vendor/ directory which will contain
the packages to install. This uses --no-index and --find-links so will
not resolve for any dependencies from pypi. For this reason there is
assumed confidence that the vendor/ directory will contain all
of the dependencies we need.

scripts/aws_install_dependencies.sh

@@ -2,4 +2,4 @@
 
 echo "Install dependencies"
 cd /home/notify-app/notifications-admin;
-pip3 install --find-links=wheelhouse -r /home/notify-app/notifications-admin/requirements.txt
+pip3 install --find-links=vendor -r /home/notify-app/notifications-admin/requirements.txt