Removed unused internal request lib

refs 3f0bab4389

- the internal `request` lib we had was replaced with `@tryghost/request` in
  the referenced commit
- this lib was not deleted, so it's still lingering around
- this commit deletes that file to clean it up

core/server/lib/request.js

@@ -1,25 +0,0 @@
-const got = require('got');
-const _ = require('lodash');
-const validator = require('@tryghost/validator');
-const errors = require('@tryghost/errors');
-const ghostVersion = require('@tryghost/version');
-
-const defaultOptions = {
-    headers: {
-        'user-agent': 'Ghost/' + ghostVersion.original + ' (https://github.com/TryGhost/Ghost)'
-    }
-};
-
-module.exports = function request(url, options) {
-    if (_.isEmpty(url) || !validator.isURL(url)) {
-        return Promise.reject(new errors.InternalServerError({
-            message: 'URL empty or invalid.',
-            code: 'URL_MISSING_INVALID',
-            context: url
-        }));
-    }
-
-    const mergedOptions = _.merge({}, defaultOptions, options);
-
-    return got(url, mergedOptions);
-};