The "disabled" property of RightButtons was not handled.

* Due to race condition when showing modal, buttons were added to
previous Toolbar.

* Minor refactor, moved `updateStyles` from BaseReactActivity to
StyleHelper class since it's now also used by RnnModal

Due to race condition between SetupToolbarButtonsTask and
onCreateOptionsMenu buttons did not get set for first pushed screen.
In order to set buttons we need a ref to Menu which is set in
onCreateOptionsMenu. Sometimes onCreateOptionsMenu got called after
onCreate of our activity where we setup the toolbar.

Fix invalid import.

Toolbar buttons not updating
Pushes into BottomTabActivity not always working
Modal not closing properly when back pressed

# Conflicts:
#	package.json

Minor refactor after merging #52.

Add support for hiding the Toolbar on Android

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
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# the commit.

Add support for bottom tabs in Android

Removed propTypes from example-redux screens

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

Add support for passing props to a screen in Android

Anything passed in a navigator event in a 'passProps' object will be serialized into the Java side Screen object as a HashMap<String, Object>. When RctView starts the React root the props are deserialized into the Bundle passed as props, along with the navigation info. Due to React and Java limitations, JS arrays of arrays are deserialized as dictionaries by index, and arrays of multiple types are not supported.