mime_types now behaves as wrapper for mimetypes.

mimetypes does not allow overwriting stored values (stored in
mimetypes.knownfiles). This wrapper allows us to define our own mappings and
fallback on mimetypes if mime type is not found.
fix bug 915314: Use preformatted styling for code in script warning messages
Merge pull request #1520 from lmorchard/915314-kumascript-error-styling

fix bug 915314: Use preformatted styling for code in script warning messages
Merge pull request #1519 from nhenezi/mime_type-improvements

mime_types now behaves as wrapper for mimetypes.