update venv command

tests/test_10_venv.py

@@ -0,0 +1,11 @@
+class VenvOptions(object):
+    python = '2.6.6'
+    all = False
+
+def test_venv():
+    from pythonbrew.commands.venv import VenvCommand
+    c = VenvCommand()
+    c.run_command(VenvOptions(), ['create', 'aaa'])
+    c.run_command(VenvOptions(), ['list'])
+    c.run_command(VenvOptions(), ['use', 'aaa'])
+    c.run_command(VenvOptions(), ['delete', 'aaa'])