Add --version option to validator binaries

pre_commit/clientlib/validate_base.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 
 import argparse
 import os.path
+import pkg_resources
 import re
 import sys
 
@@ -71,6 +72,14 @@ def get_run_function(filenames_help, validate_strategy, exception_cls):
         argv = argv if argv is not None else sys.argv[1:]
         parser = argparse.ArgumentParser()
         parser.add_argument('filenames', nargs='*', help=filenames_help)
+        parser.add_argument(
+            '-V', '--version',
+            action='version',
+            version='%(prog)s {0}'.format(
+                pkg_resources.get_distribution('pre-commit').version
+            )
+        )
+
         args = parser.parse_args(argv)
 
         retval = 0