* Support subtitle FontFamily on size on Android

Font family can be either a .ttf/.otf asset or one of the default font families:

* sans-serif (regular)
* sans-serif-light
* sans-serif-condensed
* sans-serif-thin
* sans-serif-medium

* update docs

* testing

* test

* try fix props on topTabs

* Test xml menu

* Add titleBarHeight

* Remove test

* Add to StyleParams

* Add topTabsHeight

* Fix styleParams type

* Add navBarFontBold

* Add typeface package

* Remove unused debugging

Fixes #1609

Usage:
    navBarCustomView: 'example.CustomTopBar', // registered component name
    navBarComponentAlignment: 'center' // 'center'/'fill'

* Add font family support on bottom tabs

* import missing classes

* import missing class

* update document

* Support customize icon for left nav button in android

* Add navBar navBarTextFontSize support for android

* 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.

* navBarButtonColor was not applied to custom initial left button
* Dynamic custom button didn’t work
* Setting default icon (like menu or back button) after a custom icon was used didn’t work

This commit adds support for the following style properties:
titleBarTitleFontFamily - string, font name in assets
titleBarTitleTextCentered - boolean, default is false

* adding support for android centered title and custom font

* PR feedback

Support customize icon for left nav button in android

* Fadeout translucent drawable when collapsing

* Change default scrim color to none
* Fade out translucent when collapsingToolBarCollapsedColor is not defined

Animate between translucent and solid background in collapsed titlebar

* Don’t create SideMenu button automatically on Android

* Remove left button and add it dynamically

* Fix resetTo animation on Android

Up until now resetTo would destroy the current stack and create a new
one. This was an easy implementation but resulted in jurky
(none existent) animations.
This commit changes resetTo behavior. Instead of recreating the stack,
the we reset to is pushed to the stack, and the other elements are
removed when show animation ends.

* Move event emmiter logic out of Application

* Implement searchView

Usage:
```js
rightButtons: [
      {
        id: 'searchView',
        label: 'Search',
        hint: 'Search...'
      }
    ]
```

* Translucent TitleBar

* Collapse TopBar

* Less noticeable translucent effect

* Implement ScrollViewDetector

* Collapse on fling

* Collapse on touch up

Complete collapse on touch up instead of fling

Also removes ContextualMenu after it is dismissed