Providing User-Agent for using maps.wikimedia.org

[philgyford]

In #265 the ability to maps.wikimedia.org was added. Maybe since then the Terms of Use have changed, but they now say:

If you are developing an application that uses the Wikimedia Maps service, you must provide a valid HTTP User-Agent that includes your application, version, and sufficient information to easily contact you (e.g., your email address).

The following are prohibited on the Wikimedia Maps service:

1. Excessive downloading (such as downloading significant areas of tiles for later offline usage)
2. Accessing the service without a proper HTTP User-Agent or HTTP referer
3. Using the service without compliance with any license or copyright terms

I may have missed something obvious, but I can't see a way to specify a user-agent when adding a tile layer.

[brunob]

Doesn't seems related to this project, since the tiles are downloaded by the clients, closing feel free to comment if you need.