Previously, both the curl and HTTP request snippets would ignore
a parameter with no value, for example from the query string of the
url http://localhost:8080/foo?bar.
This commit updates both snippets so that such parameters are
included in the generated snippet, including a multi-part request
that is uploading form data and a field in the form has no value.
Additions have been made to the tests for both snippets.
While the request parameters snippet correctly handled parameters with
no value, there was no test verifying that this was the case. One
has been added in this commit.
Closes gh-200