support pick combined with matchBy
support pick combined with matchBy

This lets you use pick/pickOld/pickNew to scope down before running the
matchBy.

This provides part of the same functionality as #241, but that PR also
has better support for `matchBy: 'class'` and `matchBy: 'id'`, which we
should incorporate too.

gordonbisnor/liquid-fire,acorncom/liquid-fire,topaxi/liquid-fire,knownasilya/liquid-fire,jamesreggio/liquid-fire,givanse/liquid-fire,ember-animation/liquid-fire-velocity,jrjohnson/liquid-fire,jamesreggio/liquid-fire,ef4/liquid-fire,runspired/liquid-fire,acorncom/liquid-fire,dsokolowski/liquid-fire,runspired/liquid-fire,givanse/liquid-fire,davidgoli/liquid-fire,ember-animation/liquid-fire-core,jayphelps/liquid-fire,topaxi/liquid-fire,ember-animation/liquid-fire,ember-animation/liquid-fire,davidgoli/liquid-fire,knownasilya/liquid-fire,chadhietala/liquid-fire,byelipk/liquid-fire,jrjohnson/liquid-fire,envoy/liquid-fire,jayphelps/liquid-fire,csantero/liquid-fire,ember-animation/ember-animated,ianstarz/liquid-fire,ianstarz/liquid-fire,dsokolowski/liquid-fire,ember-animation/liquid-fire-core,twokul/liquid-fire,gordonbisnor/liquid-fire,mikegrassotti/liquid-fire,twokul/liquid-fire,ember-animation/ember-animated,monegraph/liquid-fire,byelipk/liquid-fire,ef4/liquid-fire,monegraph/liquid-fire,mikegrassotti/liquid-fire,csantero/liquid-fire,ember-animation/ember-animated,ember-animation/liquid-fire-velocity,chadhietala/liquid-fire