Improve vk manager
Add login/logout preference to settings
Remove useless code (like storing the vk token - sdk do this for us)
Fix Don't keep activities mode crashes
Merge pull request #27 from Defuera/feature/vk-login-from-settings

Improve vk manager (related to #14)
reformat
Move vkManager lisence header on top of the file
Merge pull request #30 from Defuera/feature/vk-login-from-settings

Move vkManager lisence header on top of the file