Split HTTP module into core and implementation

[acoburn]

There are instances where modules depend on org.trellisldp.http.core types but don't need the JAX-RS matchers themselves. It would be cleaner to split off everything in the org.trellisldp.http.core package into its own module: trellis-http-core. The @Trellis (or @LdpResource) NameBinding annotation should go there, too. (ref: #1000)