Adding more cities

[wrabit]

UK only has 63 cities listed.

What is the source of the data? Can the seeds be reproduced?

[khsing]

@wrabit I crawl several dataset from web, some data may be out-dated. If you found some wrong data, please help me to update it. Thanks so much.

[seche]

I updated the dataset in my pull request #51 from this source: https://download.geonames.org/export/dump/