Small change to remove rvm warning and support https


It seems that RVM has moved along in the 2 years since you've updated the project; I wanted to submit a few small changes back for you to consider.

The first is to convert .rvm to .ruby_version (which seems to be the 'new way' to say what version you want)

The 2nd is to use https instead of http to access the NPR api.

Apologies for the earlier broken pull request; I thought I had tested it, but I must have been testing against an older version.