Fix service const lookup, add thermostat services, add tests

I initially started by just fixing a bug that threw an exception when a device service name had an underscore.  Once I fixed that and got it working, I added more services that I had available for my thermostat.  I also had to change the urn for the energy_metering1 service for it to work and looks like it matches the API docs now.

In addition, I added some tests and set it up to use VCR to mock out the HTTP requests when needed.  I included a cassette I recorded from a data request from my Vera.

This is a cool project.  Thanks for putting it out here.