title: no umbrella header found for target, module map will not be generated
body: <p>When I trying build <a href="https://github.com/cybertk/CKCountdownButton" rel="noreferrer">CKCountdownButton</a> as a framework in Xcode 6.3, it complains with </p>
  
  <p><strong>warning: no umbrella header found for target 'CKCountdownButton', module map will not be generated</strong></p>
  
  <p>Then when I import this framework in other project, it failed with <strong>No such module 'CKCountdownButton'</strong></p>