python: Fix several pep8 whitespace errors.

Fix the following pep8 errors:

  E201 whitespace after '('
  E203 whitespace before ','
  E222 multiple spaces after operator
  E225 missing whitespace around operator
  E226 missing whitespace around arithmetic operator
  E231 missing whitespace after ':'
  E241 multiple spaces after ':'
  E251 unexpected spaces around keyword / parameter equals
  E261 at least two spaces before inline comment
  E262 inline comment should start with '# '
  E265 block comment should start with '# '
  E271 multiple spaces after keyword

Signed-off-by: Russell Bryant <russell@ovn.org>
Acked-by: Ben Pfaff <blp@ovn.org>

tests/test-unixctl.py

@@ -37,7 +37,7 @@ def unixctl_echo(conn, argv, aux):
 
 
 def unixctl_echo_error(conn, argv, aux):
-    assert aux ==  "aux_echo_error"
+    assert aux == "aux_echo_error"
     conn.reply_error(str(argv))