Query parameter without equals sign are not added to `Request.Query`

[pakrym]

For request http://localhost:5000/?q query collection would be empty so to check if parameter exists user would need to parse it manually. On other hand http://localhost:5000/?= works and creates item with empty name and empty value, which is semantically correct but is much less useful.

[muratg]

@moozzyk If a key doesn't have any value, just make it an empty string.

[moozzyk]

Fixed in e854d3a