AmIpFilter to support REST APIs

The AmIpFilter doesn't like REST APIs, as all operations are redirected to the proxy as a 302. Even if the proxy did relay all verbs, the filter would need to return a 307 and hope the client was enable to re-issue the verb.

The alternative is to have a dedicated part of the webapp to be unproxied, which we did with a custom filter to not relay "/ws/*", or even allow apps to register a rest endpoint directly, either in the AppReport data, or via the YARN-913 registry