Fix #100 pre release versions not shown for some packages

[gerardroche]

When a package pre release version supports the same platforms then there is only one item in versions:

    'versions': [
        {
            'version': '1.29.1',
            'prerelease_version': '1.30.0-beta.2',
            'platforms': ['*'],
            'st_versions': ['3', '4']
        }
    ],

Q. Do I need to include the app.css and app.js files?

Before

After