ensure traceback is imported, added IOError message mappings and HTTP error message mappings.
ensure traceback is imported, added IOError message mappings and HTTP error message mappings.

Added spaces back before colons.
added spaces back within braces.
further changes to whitespace since git does not ignore whitespace.
Merge pull request #13 from jwest-apigee/master

Fix missing traceback error, added error number mappings.