[iOS] Added ability to set static(root) background image

Currently startApp is called from global context which results in the
app being launched when headlessJs tasks run in the background.
In order to support this use case, while not breaking existing users,
this commit adds two mechanisms which should help users detrmine if
the native Activity is running and startApp can be called safely.

1. RNN.appLaunched event is emitted is SplashActivity starts and react
   context has already been created. This is the use case of openeing
   the app while headless js task was started or has just finished and
   react context is in a "pasued" state.

2. Navigation.isAppLaunched() convenience method has been added.
   It returns a promise which when resolved, indicates if the app
   is launched and we should show the ui or not.

Usage

import {Navigation, NativeEventsReceiver} from 'react-native-navigation';

Promise.resolve(Navigation.isAppLaunched())
  .then(appLaunched => {
    if (appLaunched) {
      startApp();
    } else {
      new NativeEventsReceiver().appLaunched(startApp);
    }
  });

function startApp() {
  Navigation.startTabBasedApp({ ... });
}

This fixes issues with other React Native views which rely on the view controller hierarchy.

* Move logic for tap background to dismiss out of background color view

This allows for tapping the background without setting a color here, meaning this feature can be enabled with one less view in the view hierarchy

* Only allow taps on views that aren't the React view

This allows for taps on any background view, visual effect view, color tint view, etc, but not on the content.

Yarn apparently still has issues with relative paths.

OCD made me do it.

* Added tapBackgroundToDismiss to LightBox screens

* Updated LightBox readme

* Formatting updates

* Fixed ios selector

* Updated animationEnd hide method

added a missing comma in the 'style object format' so to help users who copy/paste this code block

Fixes #1411
Each time a color attribute is set in AHBottomNavigation, all items in
the BottomTabs are recreated. If a badge is set, it is animated each
time items are recreated. This behaviour can even be seen in the gifs
in the repo https://github.com/aurelhubert/ahbottomnavigation

* Fixed lightbox status bar color override on Android

* Added missing imports

added 03d380f8a9 back and also applied this fix https://github.com/wix/react-native-navigation/issues/428#issuecomment-278268928 on top of it

Removing duplicate property

React is now migrating away from React.PropTypes starting from v15.5.0
More info:
https://facebook.github.io/react/blog/2017/04/07/react-v15.5.0.html

Can be null if returning from another app and our activity wad destroyed in background

* [iOS] Added fade transition animation between screens

* Update docs for #1367

* Fix iOS drawer status control

* Prevent MMDrawerController disabling UI interaction when accidentally assigning a nil drawer controller and toggling that drawer

* setDrawerEnabled with params side and enabled

* Tweak docs, small RCCDrawerController fix

* Correct indents

* Correct indents

* Fix title bar not displayed if it was initially hidden

Also cleaned up VisibilityAnimator.

* Move visibility animator into topBar

This reverts commit 7919e65932.

Also cleaned up VisibilityAnimator.

* Fix disabledBackGesture.

This `return self._disableBackGesture ? self._disableBackGesture : YES;` check is incorrect, it's the same as `true ? true : true;`.
Also `_disableBackGesture` was never set. We should just `return disabledBackGestureBool` (bool value of the prop).

* [iOS] Enable back swipe gesture when a navBar is hidden. Resolves this issue: https://github.com/wix/react-native-navigation/issues/930

added 03d380f8a9 back and also applied this fix https://github.com/wix/react-native-navigation/issues/428#issuecomment-278268928 on top of it

* Revert accidental commit: 3cdb1b37f6