Use 'syntax' as rule name upon syntax errors

tests/test_cli.py

@@ -530,7 +530,7 @@ class CommandLineTestCase(unittest.TestCase):
         out, err = sys.stdout.getvalue(), sys.stderr.getvalue()
         self.assertEqual(out, (
             'stdin:2:10: [error] syntax error: '
-            'mapping values are not allowed here\n'))
+            'mapping values are not allowed here (syntax)\n'))
         self.assertEqual(err, '')
 
     def test_run_no_warnings(self):

yamllint/linter.py

@@ -180,7 +180,7 @@ def get_syntax_error(buffer):
     except yaml.error.MarkedYAMLError as e:
         problem = LintProblem(e.problem_mark.line + 1,
                               e.problem_mark.column + 1,
-                              'syntax error: ' + e.problem)
+                              'syntax error: ' + e.problem + ' (syntax)')
         problem.level = 'error'
         return problem