Consider server and browsers with creation url

[bhstahl]

Right now the creation extension omit's thee protocol from a created url, which can cause some issues using tus-js-client server side (https://github.com/tus/tus-java-client/issues/10#issuecomment-258384118). We should consider a new approach that works in the browser and server

[Acconut]

tusd will derive the protocol from the request (https://github.com/tus/tusd/blob/master/unrouted_handler.go#L633-L637). Later this value may be overwritten by the X-Forwarded-Proto header (https://github.com/tus/tusd/blob/master/unrouted_handler.go#L645-L647) which is commonly used by proxies. A similar approach may be useful tus-node-server.

[bhstahl]

Like that option @Acconut, we'll follow suit