Refs #10566. Adding linux version of getOSVersionReadable.
Refs #10566. Adding code that should work for mac and windoze
Merge remote-tracking branch 'origin/master' into feature/10566_getOSVersionReable
Re #10566. Adding implementation for windows and mac.
Refs #10566. Check for the files on every os.
Merge remote-tracking branch 'origin/master' into feature/10566_getOSVersionReable
Merge pull request #69 from mantidproject/feature/10566_getOSVersionReable

Add ConfigService::getOSVersionReadable()