Add GraphQL queries for find_groups()

[schloerke]

Will eventually drop support for the following fields of meetupr::find_groups():

• organizer_id and organizer_name
• resource ... does not makes sense for GraphQL output
• localized_location stored as location and localized_country_name stored as country. These could be found via

query($lat: Float!, $lon: Float) { 
  findLocation(lat: $lat, lon: $lon) { 
    localized_country_name
    localized_location
  }
}

• Fixed in later commits. May cause rate-limit issues. Fixes GraphQL: Groups needs followup query for location information #129