Refactored create_or_update_from_dict into separate methods
Refactored create_or_update_from_dict into separate methods

Allows for calling Proposal#update_from_dict elsewhere, for example, when
updating a proposal with information extracted from a Document.

cityofsomerville/citydash,cityofsomerville/citydash,cityofsomerville/cornerwise,cityofsomerville/cornerwise,codeforboston/cornerwise,cityofsomerville/cornerwise,codeforboston/cornerwise,codeforboston/cornerwise,cityofsomerville/citydash,codeforboston/cornerwise,cityofsomerville/citydash,cityofsomerville/cornerwise