Updating the ability to trigger server instance backups

Please note, there is a breaking change here!

This was thanks to the work by Phiipp Dolder. The new methods available are as follows:

• string TriggerServerInstanceBackup(BackupOptions backupOptions);
• string GetBackupStatus();

The TriggerServerInstanceBackup method is a breaking change as it will be replacing the old method:

• bool TriggerServerInstanceBackup(string fileName);

This release will become Nuget package version 0.3.4