Add module for Etsy API using OAuth 1.0a

[al-the-x]

• Get started!
• Research required fields:
  • api_key (for all requests)
  • client_id (for auth'd requests)
• Research OAuth 1.0a with hello.js
  • Twitter
  • Tumblr
  • Dropbox
• Register a new Module with hello.js using:
  • OAuth 1.0a
  • default proxy
  • JSONP (to bypass CORS)
  • endpoints for auth, request, and token
  • endpoint mapping for standard requests: . . .
  • Scaffold tests? Where should they go?
  • Setup local OAuth proxy via Browser-Sync?
• Add example implementation to demos/
• Add tests for Etsy module? Where do per-module tests live?
• Update documentation... Where is the per-module documentation?

Resources

• Etsy API docs
  • Getting Started: OAuth
• Initial request: Add module for Etsy.com? #268

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This change is

[al-the-x]

Having trouble tracking down functional tests for the modules. I found tests/specs/e2e/modules.js, but that appears to be trivial sanity checks. Advice, @MrSwitch?

[MrSwitch]

Mock up a resource reponse and name it tests/specs/stubs/[network]/[method]/[path].json, i.e. https://github.com/MrSwitch/hello.js/tree/master/tests/specs/stubs/twitter/get then add the expected transformation of the formatted data too
https://github.com/MrSwitch/hello.js/tree/master/tests/specs/unit/modules

If you have more tests in mind please include.