Implement thermostatting test

[davidlmobley]

Gilson pointed out we should be able to test whether the MC is working properly by turning off all thermostatting and running constant energy MD and using the MC to "thermostat" the system (e.g. without velocity randomization after moves). This is probably a good test to set up (a slow test to run locally, most likely) if we can implement it without too much wrangling.