Update README.md
Add method for deauthorization
Add timeout interval
Create loger protocol
Fix crash
Create logger protocol
Post notification
Add method to download file
Fix comments
Merge pull request #5 from Constantine-Fry/fry-branch

Fry branch
Make += public
Make some properties variable
Fix keychain for release builds
Add method to download images
Log more info about response
Fix possible crash
Don't pass access token if it can't be saved in keychain
Implement printable protocol
Fix double processing of URL
Implement demo app