Move dashboard presentation to the client side

Currently, we have an uncomfortable split between parts of the dashboard being rendered on the client and server sides. Our only two current widgets (lvalue and graph widgets) are quite dynamic/interactive, so their rendering is done completely client side. However, the layout of our dashboards is currently being done using twisted.web templates. Server side templating definitely has its place, but doesn't work too well for laying out the dashboard. Moving this to the client side will allow our layout to be much more responsive, and remove a significant amount of uncomfortable workarounds we currently have in place in order to share the rendering between the client and server side.

This is based on a discussion @hodgestar and I had last week.