D-14493

Description:
If a user sends a query string through repose that starts with an '&' (e.g. http://service.api.com/path/to/resource?&t=1375304890) Repose forwards out a mangled query string (http://service.api.com/path/to/resource?=&t=1375304890)which might cause and origin service to throw a 500 error.

Acceptance Criteria: 
Invalid query parameters are removed from the request before the request is sent to the origin service. 
(we will remove the first ampersand)
The exact query parameter above is in a test case that fails prior to coding and passes after coding.

To clarify, the query parameters we were seeing weren't technically invalid, just meaningless. The code change below removes any query parameter which uses an empty string as a key.