go.tools/cmd/godoc: permit dash and capitals in redirect paths
go.tools/cmd/godoc: permit dash and capitals in redirect paths

This was causing some /blog/foo-bar-baz paths to 404.

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/13640044

karmakaze/go.tools,karmakaze/go.tools,karmakaze/go.tools,lattera/go.tools,chenjianlong/go.tools,chenjianlong/go.tools,karmakaze/go.tools,lattera/go.tools,karmakaze/go.tools,chenjianlong/go.tools,lattera/go.tools