When starting new activity after previous activity showed modals
and did not dismiss them. The modal controller still had
registered modals even though we can't go back in the activity stack.

* Use navBarButtonColor to tint Toolbar instead of buttonsTint

* Use navBarTextColor to tint Toolbar instead of titleColor

Since Toolbar icons' height is set according to Toolbar height,
We need to ensure the call to `setupToolbar` from `onCreate` is
called after the Toolbar is measured.

navigatorEventID was generated from navigator, probably by mistake.
This caused a bug which was noticeable when showing modals from
a pushed screen. In this case two components shared the same
navigatorEventID thus they both responded to events from native.

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.

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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# Lines starting with '#' will be ignored, and an empty message aborts
# 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