Minor refactoring for tool tasks

- Don't scan for translations on initialization in TranslationPageGenerator in order to speed up startup time of ToolsRunner
- Extract checking for null / empty array of File#listFiles into a separate method
- Move single method of RuntimeUtils into Utils class

src/main/java/fr/xephi/authme/util/Utils.java

@@ -48,4 +48,13 @@ public final class Utils {
             return false;
         }
     }
+
+    /**
+     * Return the available core count of the JVM.
+     *
+     * @return the core count
+     */
+	public static int getCoreCount() {
+		return Runtime.getRuntime().availableProcessors();
+	}
 }