increasing difference for modifcation time tests

one second is sometimes not enough when using a slow storage connection,
three seconds is working better (at least when testing against S3)

tests/lib/files/storage/storage.php

@@ -168,10 +168,10 @@ abstract class Storage extends \PHPUnit_Framework_TestCase {
 		$this->assertTrue($this->instance->isReadable('/lorem.txt'));
 		$ctimeEnd = time();
 		$mTime = $this->instance->filemtime('/lorem.txt');
-		$this->assertTrue($this->instance->hasUpdated('/lorem.txt', $ctimeStart - 1));
-		$this->assertTrue($this->instance->hasUpdated('/', $ctimeStart - 1));
+		$this->assertTrue($this->instance->hasUpdated('/lorem.txt', $ctimeStart - 3));
+		$this->assertTrue($this->instance->hasUpdated('/', $ctimeStart - 3));
 
-		$this->assertTrue(($ctimeStart - 1) <= $mTime);
+		$this->assertTrue(($ctimeStart - 3) <= $mTime);
 		$this->assertTrue($mTime <= ($ctimeEnd + 1));
 		$this->assertEquals(filesize($textFile), $this->instance->filesize('/lorem.txt'));
 
@@ -185,10 +185,10 @@ abstract class Storage extends \PHPUnit_Framework_TestCase {
 		$mtimeEnd = time();
 		if ($supportsTouch !== false) {
 			$mTime = $this->instance->filemtime('/lorem.txt');
-			$this->assertTrue(($mtimeStart - 1) <= $mTime);
-			$this->assertTrue($mTime <= ($mtimeEnd + 1));
+			$this->assertTrue(($mtimeStart - 3) <= $mTime);
+			$this->assertTrue($mTime <= ($mtimeEnd + 3));
 
-			$this->assertTrue($this->instance->hasUpdated('/lorem.txt', $mtimeStart - 1));
+			$this->assertTrue($this->instance->hasUpdated('/lorem.txt', $mtimeStart - 3));
 
 			if ($this->instance->touch('/lorem.txt', 100) !== false) {
 				$mTime = $this->instance->filemtime('/lorem.txt');
@@ -203,11 +203,11 @@ abstract class Storage extends \PHPUnit_Framework_TestCase {
 		clearstatcache();
 		$mtimeEnd = time();
 		$mTime = $this->instance->filemtime('/lorem.txt');
-		$this->assertTrue(($mtimeStart - 1) <= $mTime);
-		$this->assertTrue($mTime <= ($mtimeEnd + 1));
+		$this->assertTrue(($mtimeStart - 3) <= $mTime);
+		$this->assertTrue($mTime <= ($mtimeEnd + 3));
 
 		$this->instance->unlink('/lorem.txt');
-		$this->assertTrue($this->instance->hasUpdated('/', $mtimeStart - 1));
+		$this->assertTrue($this->instance->hasUpdated('/', $mtimeStart - 3));
 	}
 
 	public function testSearch() {