feat(index.js): export ToastContainer and ToastMessage

export ToastMessage for future subclassing

BREAKING CHANGE
  ToastContainer is put into exports and no longer a default export
chore(webpack.config.js): remove React as externals
chore(client): load jquery from cdn
feat(ToastMessage): hook onClick handler
feat(ToastMessage.jQuery): with jQueryMixin
feat(jQueryMixin): add show props and hook to componentDidMount
feat(ToastMessage): add handleMouse{Enter/Leave} for internal api
feat(jQueryMixin): hook hover logic into handleMouse{Enter/Leave}
feat(ToastMessage::hideToast): hookup correct behavior
feat(ToastMessage): hookup remove toast from state
feat(ToastContainer): add clear interface
style(ToastContainer): use template string
feat(ToastMessage): add closeButton props support
style(src): underscored for private methods