Begins implementation of new CardContact to handle Zap cards as contacts

* adds factory_girl for non-fixture tests
Adds FactoryGirl for creating non-AR test objects

* adds unit tests for basic CardContact
Implements retrieval of ExchangedCards

* pulls ExchangedCards and creates CardContacts from them
Adds merging of contacts and tap card contacts -- wip
Adds display of Tap indicator for card contacts.
Fixes display of structs in CardContact
Adds merging of contacts and tap card contacts into contact display
Adds Tap card icon