Fix missing accept header

Set accept to */* if no accept header was sent
Merge pull request #16 from tiwoc/missing-accept-header

Fix missing accept header
Fix PathParameters for WebService filter

Previously, filters defined for WebServices used their own means of
wrapping http.ResponseWriter and http.Request. This lead to
req.PathParameters returning no parameters. This commit applies the
usual wrapping as defined in route.go when calling WebService filters.
Merge pull request #19 from tiwoc/fix-webservice-filter-params

Fix PathParameters for WebService filter