Disabled mirage logging in tests to fix Travis runs

mirage/config.js

@@ -51,7 +51,7 @@ export function testConfig() {
     // this.urlPrefix = '';    // make this `http://localhost:8080`, for example, if your API is on a different server
     this.namespace = '/ghost/api/v2/admin'; // make this `api`, for example, if your API is namespaced
     // this.timing = 400;      // delay for each request, automatically set to 0 during testing
-    this.logging = true;
+    this.logging = false;
 
     mockApiKeys(this);
     mockAuthentication(this);