Basic support for running server tests with shield

These changes will make sure the kibana server in tests is using shield
credentials, as are any requests made through the kbn_server test
helper.

The current credentials are hardcoded based on our internal best
practices, but they should be made configurable in the future.

This will pass credentials to ES regardless of whether shield is
actually enabled, but that will have no negative effect if shield
happens to be disabled.

test/utils/base_auth.js

@@ -0,0 +1,4 @@
+export function header(user, pass) {
+  const encoded = new Buffer(`${user}:${pass}`).toString('base64');
+  return `Basic ${encoded}`;
+}

test/utils/kbn_server.js

@@ -1,5 +1,6 @@
-import { defaultsDeep } from 'lodash';
+import { defaultsDeep, set } from 'lodash';
 import requirefrom from 'requirefrom';
+import { header as basicAuthHeader } from './base_auth';
 
 const src = requirefrom('src');
 const KbnServer = src('server/KbnServer');
@@ -24,7 +25,9 @@ const SERVER_DEFAULTS = {
     enabled: false
   },
   elasticsearch: {
-    url: 'http://localhost:9210'
+    url: 'http://localhost:9210',
+    username: 'kibana',
+    password: 'notsecure'
   }
 };
 
@@ -33,6 +36,12 @@ export function createServer(params = {}) {
   return new KbnServer(params);
 };
 
+export function authOptions() {
+  const authHeader = basicAuthHeader('user', 'notsecure');
+  return set({}, 'headers.Authorization', authHeader);
+};
+
 export function makeRequest(kbnServer, options, fn) {
+  options = defaultsDeep({}, authOptions(), options);
   return kbnServer.server.inject(options, fn);
 };