Semantic update to userAddress auth-context state value

[johngribbin]

• Up until now the default value for user address has been the string value none,
• This is used by many components to assess if the user was logged in or not.
• With this change, the default is now undefined (type undefined) and the components that utilize the userAddress value (conditional rendering etc) have all been updated to recognize this change
• This change not only makes the code more legible but I believe it is just a better practice

[johngribbin]

@Kmoneal Does changing the default state of userAddress from "none" to undefined cause any breaking changes on the backend? If not, i'd like to merge this change. Not a huge priority though, so if it does cause any hassle on backend - we can delay.