add VKontakte provider

[mpkupriyanov]

Hello Caleb!

for test client_id = 4742240

[MaximKeegan]

I have tested it on my project. Works very good! @calebd can you merge this? Thank you very much @MikhailKupriyanov!

[mpkupriyanov]

@MaximKeegan, you can use my fork for your Podfile.
pod 'SimpleAuth/VKontakteWeb', :git => 'https://github.com/MikhailKupriyanov/SimpleAuth.git'

До Caleb'a не достучаться!

[MaximKeegan]

@MikhailKupriyanov дык я так и сделал...