fix(gulp): handle gulpfile edge case

Author: tlancina

lib/cli.js

@@ -143,7 +143,14 @@ Cli.run = function run(processArgv) {
       logging.logger.debug('Gulpfile found');
       var beforeHook = argv._[0] + ':before';
       var afterHook = argv._[0] + ':after';
-      var gulp = require(path.resolve(process.cwd() + '/node_modules/gulp'));
+      try {
+        var gulp = require(path.resolve(process.cwd() + '/node_modules/gulp'));
+      } catch(e) {
+        // Empty gulpfile (or one that doesn't require gulp?), and no gulp
+        console.error('Gulpfile detected, but gulp is not installed');
+        console.error('Do you need to npm install?\n');
+        process.exit(1);
+      }
       logEvents(gulp);
 
       return Q.nfcall(gulp.start.bind(gulp), beforeHook).then(