Fix touch for creating new files

lib/files/storage/local.php

@@ -95,7 +95,7 @@ class Local extends \OC\Files\Storage\Common{
 		// sets the modification time of the file to the given value.
 		// If mtime is nil the current time is set.
 		// note that the access time of the file always changes to the current time.
-		if(!$this->isUpdatable($path)) {
+		if($this->file_exists($path) and !$this->isUpdatable($path)) {
 			return false;
 		}
 		if(!is_null($mtime)) {

tests/lib/files/storage/storage.php

@@ -257,4 +257,10 @@ abstract class Storage extends \PHPUnit_Framework_TestCase {
 		$content = stream_get_contents($fh);
 		$this->assertEquals(file_get_contents($textFile), $content);
 	}
+
+	public function testTouchCreateFile(){
+		$this->assertFalse($this->instance->file_exists('foo'));
+		$this->instance->touch('foo');
+		$this->assertTrue($this->instance->file_exists('foo'));
+	}
 }