Go 1.9 support

Merge pull request #30 from guregu/autocancel-v2

Option to cancel all request contexts automatically

tweak params a bit, add test

Merge pull request #27 from guregu/multiware-wildcard

Allow registration of multiple wildcard middlewares

support more middleware/afterware types

notably `func(http.ResponseWriter, *http.Request) context.Context`

Merge pull request #25 from guregu/newctx

Support 1.7 context package

add Serve* methods to Mux

internal folder was breaking gopkg.in

Merge pull request #16 from guregu/httptreemux

Switch router to httptreemux

fix test