docs(cli) Add Cucumber to the CLI help text

Author: mattwynne

Diff for: lib/cli.js

@@ -48,7 +48,7 @@ var argv = require('optimist').
     describe('verbose', 'Print full spec names').
     describe('stackTrace', 'Print stack trace on error').
     describe('params', 'Param object to be passed to the tests').
-    describe('framework', 'Test framework to use. jasmine or mocha.').
+    describe('framework', 'Test framework to use: jasmine, cucumber or mocha').
     alias('browser', 'capabilities.browserName').
     alias('name', 'capabilities.name').
     alias('platform', 'capabilities.platform').