(Feature) Add React components tests

[vbaranov]

Problem: Wizard has no React component tests. Solution: Add React tests in addition to smart-contracts' tests for every component and add them to Travis CI. For example, by means of https://github.com/airbnb/enzyme. We can divide this task into smaller parts and start with several components. @fvictorio @fernandomg @rstormsf please share your thoughts here.

[fvictorio]

I'll start working on this, at least to get things moving in this direction. I'll work on #442 and add tests to the refactored RadioInputField component.

[fernandomg]

I was reviewing code coverage, and this is the list of tests that can be added (I'll create an issue per task) based on what won't change between v1 & v2

• [ ] stores/ (#818)
  • CrowdsaleStore
  • ReservedTokenStore
  • TierStore
  • TokenStore
  • Web3Store
• [ ] components/Common/ (#819)
  • CrowdsalesList
  • DisplayField
  • DisplayTextArea
  • Loader
  • ModalContainer
  • NoWeb3
  • PreventRefresh
  • StepNavigation
  • TierBlock
  • TxProgressStatus
  • WhenFieldChanges
  • WhitelistInputBlock
  • WhitelistItem
• [ ] components/ (#820)
  • Header
  • Footer
  • StepTwo
• [ ] utils/ (#821)
  • alerts
  • api
  • cancelDeploy
  • copy
  • microservices