Fix for #251

Fix for #251 
- on windows paths need to be normalized - gherkin lexer files were not found

- disabled 'debug' mode of browserify - it was creating huge source map and size of bundled file was exceding > 2MB

- added optional param to the bundle script:
$ node scripts/release.js gherkinLang=XX 
i.e:
$ node scripts/release.js gherkinLang=en
By default it includes all languages