Add fast thermostat switcher

[Chumley]

Doing something with this could also address the need to display the selected thermostat on all pages, as requested in this issue:

Thermostat name on all pages

I have two thermostats, one for each level of my home. For the Detail page, it clearly shows the name of the thermostat near the top so I know which one I am looking at. When switching to any of the other pages (Analyze and Air Quality, in particular), there is no thermostat name. It would be helpful to have the name show at the top of the page as in a header that remains fixed while the rest of page allows scrolling.