To Do

currently no way to add users to challenge if they haven't already created an account
add OmniAuth and figure out how to log in automatically
- Google auth?
disable drawer nav while in tab nav
- waiting for pull request #793 to go through which will resolve this
- react-navigation/react-navigation#793
- react-navigation/react-navigation#1082
decide what to do with contacts on signup
convert app to Redux state management
style header component (Login and LoaderPage)
add spinner to LoaderPage
add spinner to AllChallenges while awaiting firebase data
deal with offline status???
remove "userLookup" from Firebase db as somewhat duplicative of "users" ('users' contains some info re challenges but not much)???
make user search case insensitive. Currently on ios search defaults to caps and emails are lower case

Completed tasks

update header block in nav sidebar (w/ profile pic, etc.)
autocomplete on TextInput does not update state (ios only?) need to fix this (turn it off?)