Add query parameter object to callback

[mstade]

From @mstade on September 18, 2015 8:28

Currently, if you match /foo/{bar} with /foo/wibble?bar=1 the value of bar sent to the callback in the params object will be wibble, and the query parameter is lost. It makes sense for path parameters to take precedence, however we shouldn't lose information so consider adding a second callback parameter specifically for query parameters; alternatively roll up the parameters into a list as #4 says. Unclear what the way forward here is.

Copied from original issue: sammyt/rhumb#13