Let Travis lint using `node make lint`, instead of a hard-coded command

make.js

@@ -1492,9 +1492,11 @@ target.lint = function() {
   var options = '--extra-ext .jsm';
 
   var exitCode = exec('"' + jshintPath + '" ' + options + ' .').code;
-  if (exitCode === 0) {
+  if (exitCode !== 0) {
-    echo('files checked, no errors found');
+    exit(1);
   }
+
+  echo('files checked, no errors found');
 };
 
 //

package.json

@@ -11,7 +11,7 @@
     "yargs": "^3.14.0"
   },
   "scripts": {
-    "test": "node ./node_modules/.bin/jshint --extra-ext .jsm ."
+    "test": "node make lint"
   },
   "repository": {
     "type": "git",