Removed UrlEncode from AppendUrlPaths method

Hi,

I was playing with https://github.com/ServiceStack/ServiceStack.Text/blob/master/tests/ServiceStack.Text.Tests/UseCases/GithubV3ApiTests.cs example.

After trying to get user "mythz" I got an error "404 not found". When I look at the url of the api call it was https://api.github.com/users%2fmythz 

After some search I found StringExtensions -> AppendUrlPaths. Removing UrlEncode solved my problem but I'm not sure if it is the real problem. The real problem might lie under UrlEncode function...

Regards