Remove WePay support from Phortune, and Restful/Httpful dependencies

Summary: Ref PHI1166. I'm documenting our dependencies, and we have approximately 5,000 lines of external code to support WePay as a Phortune provider. We don't use it, I'm almost certain it doesn't work, and we have no plans to use it in the near future. If we did pursue it, I'd probably just wrap the API in a 100-line `WePayFuture` anyway since 5K lines of dependencies to make a couple method calls is ridiculous.

Test Plan: Grepped for `wepay`, `httpful`, `restful`.

Reviewers: amckinley

Reviewed By: amckinley

Subscribers: aurelijus

Differential Revision: https://secure.phabricator.com/D20521

Author: epriestley