small ui update

- rate vs density plot updates instantly when message is received
- plot and control headers change color on rate update
full architecture integration

- socket.io is used for client-server communication instead of SSE +
XMLHTTP request
- producer implemented on server-side for user-set ramp metering rate
limits
socket.io package added for node
ign
changed port to 3000
Merge pull request #8 from natan-morar/master

architecture integration