Provisioning profiles support for contact and contact_notes fields

This adds support to the provisioner to read ```contact:``` and ```contact_notes:``` optional fields from the provisioner profiles.yaml. This allows users to maintain a consistent point of contact for a specific nodeclass (i.e. searchnode's contact is always search@company.com), and associate some extra information along with that asset as well (i.e. searchnodes contact_notes: http://wiki.company.com/wtf-is-this-thing/searchnode). If these fields aren't present in the profile, they are omitted. Additionally, this changes the 'contact' field semantics slightly; the person who provisions an asset is now set to the BUILD_CONTACT field instead of CONTACT.