Updated Makefile

Some quick info.

1. Building the site

make core
make c
make r
make python
make all

These do not deploy anything, just do local builds using the
git tags given in Makefile (or as environment variables).
Version numbers can be different for C, R and Python.

2. Test deployment

make test
make core-deploy-test / c-deploy-test / r-deploy-test / python-deploy-test

These deploy the site or subdirectory to http://www-test.igraph.org

3. Deployment

make deploy
make core-deploy-test / c-deploy-test / r-deploy-test / python-deploy-test