Non-unicode URL params are not properly urlencoded

https://github.com/Mashape/unirest-python/blob/master/unirest/utils.py#L5

If a key/value is not explicitly a unicode string in Python, it is never urlencoded. Non-unicode strings still must be urlencoded.

Open unirest/utils.py at line 5 and inspect how URL parameter keys and values are encoded when they are not explicit Unicode strings. Confirm that non-Unicode strings are URL-encoded consistently, and verify the behavior with the project's existing checks.

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