Fixed Modal focus management

Fix the focus not returning to the button that caused the MovieEditor modal to open after its been closed

Fixed TabList focus jumping

Fix the jumping of focus back to the TabList whenever one of the Movie action buttons is clicked

Added focus management to Movie Wishlist when movies added

Added doFocus to the TabList on MovieWishlist.js so that it always autofocuses on componentDidMount as well

Add focus management to TabList and refactor to use aria-activedescendant

Added a ref the the Tablist so that when navigating to the Movie Browser it automatically focuses the tablist on componentDidMount

Changed the TabList to use aria-activedescendant instead of the roving tabIndex pattern in an attempt to better keep the VoiceOver cursor aligned with the browser focus

Manage focus on Movie Wishlist when no movies added

Added a ref the the Add Some Movies link on the Movie WishList page that is automatically focused on componentDidMount when it exists

Fixed remaining Modal a11y issues

Fixed remaining issues with Movie Editor Modal

Replaced Modal with react-modal

Replaced Modal with use of react-modal, an already accessible Modal component from reactjs.

Added MovieToolbar toolbar widget

Added a MovieToolbar component containing a toolbar widget for the Movie actions buttons

TabList Legend added

Added a hidden legend tag to describe the tablist for screen readers

TabList keyboard interaction

Added keyboard navigation functionality to the TabList per the WAI ARIA Tab List Design Pattern requirements