add seznam.cz as identity provider

[tlamr]

Hello guys,

I started to use scribejava with seznam.cz as oauth 2.0 provider and it works perfectly.
Thanks for your hard work!
Adding it as pull request with preconfigured api class.

cc @ondras

[ondras]

Please change the profil.seznam.cz hostname in example calls to login.szn.cz. We had this wrong in our examples and are working on fixing the documentation.

[tlamr]

ok, great, thanks @ondras ! :)
changed

[tlamr]

Hello @kullfar, how are you?
Would you consider merging this contribution or is there something more I need to do?

Cheers,
Tomas

[s-gromov]

Hi @tlamr , I'm ok, thank you! I was just a bit busy lately. I hope to return soon.