Figure out a way to merge all the new 2013 stuff in the Schemas namespace with the new FieldInfos objects from the new 2010 Setup namespace

[taoneill]

Ideally, we should enhance FieldInfos to be more complete (e.g. TaxonomyFieldInfo, etc.) and collaborate with/reuse the new Schemas utils so that we don't have to depend on any Element.xml.

Basically, we want:

1. Create FieldInfo object that hold all field schema metadata as a static "constant" object in your Contracts project
2. Use a FieldHelper with capabilities similar to ContentTypeHelper to EnsureField(FieldCollection, FieldInfo)

This way we can provision fields easily on a site collection or on a list. This is related to #1, where some things that @FranckyC or @yohanb added to ListHelper don't follow the "Ensure"/"Add if not exists" philosophy of ContentTypeHelper.