Prepare for React 16.

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.

Create a new React Component for displaying a list of dial-in
numbers. The Component will fetch the numbers from a new
numberRetreviewUrl key/value set in config. If not present in
config, the Component will not be displayed.

@virtuacoplenny, the changes of this commit are not necessarily in
source code that you introduced in
https://github.com/jitsi/jitsi-meet/pull/1499 but I saw violations in
files modified in the PR which I had to read in order to understand the
PR.

Converting the invite modal includes the following:
- Creating new react components to display InviteDialog. The
  main parent components are ShareLink and PasswordOverview,
  the later handles displaying lock state and password editing.
  These components do not make use of atlaskit as the component
  for input does not yet support readonly, so for consistency
  within the modal content no atlaskit was used.
- Using redux for keeping and accessing lock state instead of
  RoomLocker.
- Publicly exposing the redux action lockStateChanged for direct
  calling on lock events experienced on the web client.
- Removing Invite, InviteDialogView, and RoomLocker and references
  to them.
- Handling errors that occur when setting a password to preserve
  existing web funtionality.