DialInNumbersForm has been modified to display a conference id to be used for
dialing into the conference. The changes include:
- Requesting the conference id and adding the conference id to the redux store
- Displaying the conference id in DialInNumbersForm
- Modifying the copy behavior to support copying the new message to clipboard
- DialInNumbersForm does not display until all ajax requests have completed
  successfully. This eliminates the need for the REQUESTING state.