add OC_Geo class

lib/geo.php

+<?php
+/**
+ * Copyright (c) 2012 Georg Ehrke <ownclouddev at georgswebsite dot de>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+class OC_Geo{
+	/*
+	 * @brief returns the closest timezone to coordinates
+	 * @param (string) $latitude - Latitude
+	 * @param (string) $longitude - Longitude
+	 * @return (string) $timezone - closest timezone
+	 */
+	public static function timezone($latitude, $longitude){	
+		$alltimezones = DateTimeZone::listIdentifiers();
+		$variances = array();
+		//calculate for all timezones the system know
+		foreach($alltimezones as $timezone){
+			$datetimezoneobj = new DateTimeZone($timezone);
+			$locationinformations = $datetimezoneobj->getLocation();
+			$latitudeoftimezone = $locationinformations['latitude'];
+			$longitudeoftimezone = $locationinformations['longitude'];
+			$variances[abs($latitudeoftimezone - $latitude) + abs($longitudeoftimezone - $longitude)] = $timezone;
+		}
+		//sort array and return the timezone with the smallest difference
+		ksort($variances);
+		reset($variances);
+		return current($variances);
+	}
+}
\ No newline at end of file