Fix broken URLInfo.query_map attribute

[chosak]

Accessing the URLInfo.query_map attribute generates a RecursionError due to a bug in the URLInfo.query_to_map method. This commit fixes that and adds tests to validate the documented behavior.

I remembered to:

• [x] Update or add unit tests if needed
• [x] Made sure stray files or whitespace didn't get committed
• [x] Read the guidelines for contributing

Changes:

• Fix bug in URLInfo.query_to_map
• Add unit tests for URLInfo.query_map