Allow authentication to be method-specific

When defining authenticated routes, it is now possible to define
`GET:/some/route`, which adds authentication for GET operations.
Authroutes in the format `/some/route` still work and add authentication for
all methods. Both formats can even be combined, with method-specific
authentication overruling method-agnostic rules.
Merge pull request #6 from icemobilelab/feature/per-method-auth

Allow authentication to be method-specific