0.5-alpha Ability to scan folders for installed games (Windows) + other fixes

• add ability to define installed games "root" folders in config #26
• scanning folders feature that primarily try to match game folders with owned games titles and then searches for close matches (one deep level)
• optimized managing of scanning in periodic checks.
• fixed launching for some games that requires executable directory as working directory
• (fix) remove credentials if they are expired
• ignore incomplete game info from humblebundle API #31

WARNING: This is alpha release, there is no warranty for anything. I'm not responsible for any false positives with executable matching. Use with caution.
In case of not detecting games or false positives - please create an issue.