Timeouts for Proxy and UrlTemplate providers
Added an optional parameter "timeout" for Proxy and UrlTemplate providers:

- timeout (optional)
    Defines a timeout in seconds for the request (if not defined, the global default timeout setting will be used).

Example configuration:

{
    "name": "proxy",
    "url": "http://tile.openstreetmap.org/{Z}/{X}/{Y}.png",
    "timeout": 10
}
Merge pull request #178 from rburhum/timeouts

Timeouts for Proxy and UrlTemplate providers