Dog Image and NSuserdefaults

Added NSuser defualts which store dogName, dogImage,
phoneNumberCreditCardEntered as bool, dogInfoEntered as bool
The latter booleans help us know if the user has entered that info yet
or not. I added conditions that skip those sections if they have been,
including if the user opens the app while already logged in, it goes
right to the Create Walk screen.
I added a Clear Defaults button the Menu view controller which clears
the NSuser defaults and lets you go through the flow again