Returns all environments in the project, in pages of 20.

A successful response looks like:

{
  'err': 0
  'result': {
    'page': 1,
    'environments': [
      // where each environment has the shape:
      {
        'id': 1,
        'project_id': 123,
        'environment': 'production',
        // visibility of the environment in the app (can either be 1 or 0)
        'visible': 1
      },
      ...
    ]
  }
}