Changed platform-dependent logging directories.

Changed the directories for Windows, Linux and Mac to the following
(using environment variables according to QSettings documentation):

Windows: %APPDATA%/ORGANISATION_NAME/APPLICATION_NAME/logging_record.log

Mac:
$HOME/Library/Preferences/com.ORGANISATION_NAME.APPLICATION_NAME.logging_record.log

Linux:
$HOME/.config/ORGANISATION_NAME/APPLICATION_NAME/logging_record.log
Merge pull request #3 from jonathanritchie/develop

Changed platform-dependent logging directories.