Rename properties to match JAX-RS annotations

Right now we have `gp:uriTemplate` and newly introduced `gp:accept`. Their semantics are the same as of `@Path` and `@Consumes` annotations in JAX-RS:
https://docs.oracle.com/cd/E19798-01/821-1841/gipzh/index.html

So it would make sense to align the GP vocabulary with JAX-RS by renaming the properties to `gp:path` and `gp:consumes`.
