ModVersionFetcher will now return a MissingVersion in case of an exception
instead of letting it propagate upwards.
Also added a generic try/catch to the VersionChecker itself, just in case
any unchecked exception might be triggered inside the thread and at least
not logged correctly.
Reworked whole Version Checker with an extensible interface to add any other service later on easier.
The version checker now has its own config file, to collect the different options and extract them from the main config file.
In that you can specify how fine the versions should be checked.
