Remove superfluous resolve

Fixes openapi-contrib#46

Author: tswaters

lib/generator.js

@@ -145,7 +145,6 @@ const generateOperationFiles = config => new Promise((resolve, reject) => {
     Promise.all(
       _.map(files, (operation, operation_name) => generateOperationFile(config, operation, operation_name))
     ).then(resolve).catch(reject);
-    resolve();
   });
 });