From trying to debug this on IRC, it appears that:
[12:31:56] <jmarinelli> open-uri only supports GET
[12:32:42] <jmarinelli> look into HTTParty, or Net::HTTP if you don't want to add dependencies
[12:32:55] <havenwood> You could use Net::HTTP from the stdlib but it's a bit unwieldy. I'd suggest HTTP.rb for a gem: https://github.com/httprb/http#readme
I will post this all to the OAuth2 Basic site. How do I close this topic?