Adds BottomTabActivity which replaces TabActivity
Adds a dependency on `com.aurelhubert:ahbottomnavigation:1.2.3`
Uses iOS tabsStyle, with additional parameter that allows toggling of whether to show the titles of inactive tabs

Navigation views such as ToolBar, StatusBar, NavigationBar can now be
customized through a static JSON defined in each screen component.

Styling options introduced in this commit:

 - ToolBar color
 - StatusBar color
 - NavigationBar color
 - Buttons tint color
 - Title color
 - Tab normal text color
 - Tab Selected text color
 - Selected tab inidicator color

Navigator.push allows us to open a new screen. Currently it starts a new Activity with the screen
as it’s root view, but this is only a temporary behaviour. The intended behaviour is similar to
View Controllers on iOS which allows you to manage view hierarchies or a stack of fragments
managed by FragmentManager on Android.