[doc] add a README.md

README.md

+    git clone git@github.com:Psycojoker/django-parltrack-votes.git
+    git clone git@github.com:Psycojoker/django-representatives.git
+    git clone git@github.com:Psycojoker/yolopol.git
+
+    cd yolopol
+    ln -s ../django-parltrack-votes/parltrack_votes/ .
+    ln -s ../django-representatives/representatives/ .
+
+    virtualenv ve
+    source ve/bin/activate
+
+    pip install -r requirements-dev.txt
+
+    python manage.py syncdb