Add Support for REI "Projects"

REI has several “projects” that allow users to monitor trail apps. There’s MTB Project, Hiking Project, Trail Run Project, and Powder Project that all return trail status information. (There’s also Mountain Project for climbers, but the API is fairly different from the others.) I’m currently using a RESTful Sensor to pull in data from these, but I thought it may be component others would be interested in as well.