Add python and platform details to --version

On Flake8 2.x we added the information about the implementation,
version, and operating system to the --version output to make helping
users easier. In short they can pretty simply just give us the output
from

    flake8 --version

And we can get a lot of the information that we need.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/flake8/options/manager.py b/src/flake8/options/manager.py
index fe3b13b..c6a3fcb 100644
--- a/src/flake8/options/manager.py
+++ b/src/flake8/options/manager.py
@@ -236,8 +236,10 @@ class OptionManager(object):
 
     def update_version_string(self):
         """Update the flake8 version string."""
-        self.parser.version = (self.version + ' (' +
-                               self.generate_versions() + ')')
+        self.parser.version = (
+            self.version + ' (' + self.generate_versions() + ') ' +
+            utils.get_python_version()
+        )
 
     def generate_epilog(self):
         """Create an epilog with the version and name of each of plugin."""