fix tests

Author: alexandresalome

src/Gitonomy/Git/Revision.php

@@ -83,7 +83,7 @@ public function getCommitHash()
      */
     public function getLastModification($path = null)
     {
-        return $this->getCommit()->getAuthorDate();
+        return $this->getCommit()->getLastModification($path);
     }
 
     /**

src/Gitonomy/Git/WorkingCopy.php

@@ -51,15 +51,15 @@ public function getDiffPending()
         $diff = Diff::parse($this->run('diff', array('-r', '-p', '-m', '-M', '--full-index')));
         $diff->setRepository($this->repository);
 
-        return $this;
+        return $diff;
     }
 
     public function getDiffStaged()
     {
         $diff = Diff::parse($this->run('diff', array('-r', '-p', '-m', '-M', '--full-index', '--staged')));
         $diff->setRepository($this->repository);
 
-        return $this;
+        return $diff;
     }
 
     /**