Moved request to lib/request

refs #9178

- next steps are to
  A: test if global.Promise works with `got` (see https://github.com/TryGhost/Ghost/pull/8988#issuecomment-351532881)
  B: re-use request utility everywhere
  C: request lib requires data/validator, which is dirty

core/server/lib/request.js

@@ -2,7 +2,7 @@ var got = require('got'),
     Promise = require('bluebird'),
     _ = require('lodash'),
     validator = require('../data/validation').validator,
-    common = require('../lib/common');
+    common = require('./common');
 
 module.exports = function request(url, options) {
     if (_.isEmpty(url) || !validator.isURL(url)) {

core/server/utils/image-size.js

@@ -2,7 +2,7 @@ var debug = require('ghost-ignition').debug('utils:image-size'),
     sizeOf = require('image-size'),
     url = require('url'),
     Promise = require('bluebird'),
-    request = require('../utils/request'),
+    request = require('../lib/request'),
     urlService = require('../services/url'),
     common = require('../lib/common'),
     config = require('../config'),

core/test/unit/lib/request_spec.js

@@ -2,10 +2,7 @@ var should = require('should'),
     sinon = require('sinon'),
     rewire = require('rewire'),
     nock = require('nock'),
-
-    // Stuff we are testing
-    request = rewire('../../../server/utils/request'),
-
+    request = rewire('../../../server/lib/request'),
     sandbox = sinon.sandbox.create();
 
 describe('Request', function () {