Fix magic REDIS_PORT variable

Its defined to `tcp://{ip}:6379` for some reason (maybe in the iojs dockerfile).

Dockerfile

@@ -1,4 +1,4 @@
-FROM iojs:onbuild
+FROM iojs:latest
 
 RUN ln -snf /usr/bin/nodejs /usr/bin/node
 RUN apt-get update && apt-get install -y python-dev build-essential python-pip git && pip install ansible && apt-get clean
@@ -10,6 +10,7 @@ RUN npm install
 RUN ./node_modules/.bin/bower install --allow-root
 
 ENV NODE_ENV production
+ENV REDIS_PORT 6379
 CMD ["node", "/srv/semaphore/bin/semaphore"]
 
 EXPOSE 80