Support per-model and per-handler remoting options

Allow the developer to pass custom `remoting` options via Model
settings, e.g.

    PersistedModel.extend(
      'MyModel',
      { name: String },
      {
        remoting: { normalizeHttpPath: true }
      });

Also add `options` arg to `app.handler`, this object is passed directly
to strong-remoting handler.
Merge pull request #433 from fabien:feature/normalize-http-path

Support normalizeHttpPath

Close #433