Use HttpRequest.uri.queryParameters.

HttpRequest.queryParameters is deprecated. (See
https://groups.google.com/a/dartlang.org/d/msg/misc/Y2UrfSEW6uA/-ZKCV-vLYUcJ)
Update start version to 0.0.7.
Merge pull request #23 from MarkBennett/update-request-to-use-uri-params

Use HttpRequest.uri.queryParameters.