Rewrite commotion-dashboard-send in lua

Requires additional pull requests in commotion-openwrt and commotion-feed (See below)!

To test:
0. See build checks in opentechinstitute/commotion-feed#38
1. Set up a gateway node
2. Use the Admin > Commotion > Bigboard Configuration to enable the dashboard and set the gatherer to 'dashboard.commotionwireless.net'
3. Wait 3-5 minutes.
4. Go to https://dashboard.commotionwireless.net in your web browser and click on the nodes displayed on the map. One of the icons should pop up a mac address corresponding to your node. (Listener script bugfix coming soon)