TODO

Move CMC API versions before deprecation
Public API Version 1 will be taken offline on November 30th, 2018.

* Use only RN elements
- Add routing (DONE 4/14)
- Portfolio Screen (DONE 4/20)
- Add Coin Screen (DONE 4/20)
- Add global market cap to top of coin list (DONE 4/28)
- Functionality to Add Coin Screen 
    -Checklist coins for user to add (DONE 5/2)
    -Change array of coins chosen to an object with coin symbols as keys and val set to '0' for asset changing (DONE 5/3)
    -Insert assets for each coin that user entered before (DONE 5/4)
    -Push to "coin": asset to firebase /portfolios/uid (DONE 5/4)
- Display Portfolio 
    -Display Coin USD Values (DONE 5/4)
    -Display Total Coin USD Values (DONE 5/7)
- Add functionality to clickable coin list with twitter integration (ADDED 5/2)
    - Display Coin Details ()
    - Twitter Feed or Button for Url
* Add auth to one time password with twilio integration 
- Pull down to refresh (all screens) (DONE 5/2)
- Spinner while coins are loading (all screens) (DONE 4/30)
- Add spacing to global cap (DONE 5/2)
- Add news screen (DONE 5/2)
- Apply AsyncStorage for user login tokens so users don't have to login everytime

Clean Up:
Use Reducer states instead of this.state in screens

Issues:
*** Adding more coins updates existing coins but erases those that weren't checked for updates