Add icons for the navigation bar at the bottom of the screen

[dyland88]

Right now, the navigation bar for switching between home and profile only has default icons. Add some nice looking icons in their place and make the text a little bigger.
Right now, we have the react-native-feather library in the project so you should be able to use some icons from that.

Example import:
import {Home, User} from 'react-native-feather';

[eris6]

i can do this!

[h1divp]

fixed by #289