createGetEndpoint / createPostEndpoint... shorthand for creating EPBase objects

Summary:
Not sure if I should make these subclasses... I probably should. Thoughts?

@SeanDunford found it tricky / verbose to create EPBase endpoints, so I built
this to make most endpoints really simple to build right out of the box.

Test Plan: Added a test.js file (included), ran it in the node console.

Reviewers: Mihai, steph, SeanDunford

Reviewed By: Mihai

CC: SeanDunford

Differential Revision: http://phabricator.palinka.me/D1394