message: Add prop-types to CurrencyDirectionChooser
diff: import React, { Component } from 'react'
  +import PropTypes from 'prop-types'
  import actions from 'redux/actions'
  import { constants } from 'helpers'
  @@ -15,6 +16,16 @@ import SubTitle from 'components/PageHeadline/SubTitle/SubTitle'
  @CSSModules(styles, { allowMultiple: true })
  export default class CurrencyDirectionChooser extends Component {
  + static propTypes = {
  + flipCurrency: PropTypes.func,
  + currencies: PropTypes.any,
  + handleSellCurrencySelect: PropTypes.func,
  + handleBuyCurrencySelect: PropTypes.func,
  + handleSubmit: PropTypes.func,
  + buyCurrency: PropTypes.string.isRequired,
  + sellCurrency: PropTypes.string.isRequired,
  + }
  +
  createOffer = () => {
  actions.modals.open(constants.modals.Offer, {
  buyCurrency: this.props.buyCurrency,
  