message: UnknownDeviceDialog: Reword the warning
diff: @@ -82,10 +82,16 @@ export default React.createClass({
  title='Room contains unknown devices'
  >
  <div className="mx_Dialog_content">
  - <h4>This room contains unknown devices which have not been
  + <h4>This room contains devices which have not been
  verified.</h4>
  -
  - <h4>We strongly recommend you verify them before continuing.</h4>
  + <p>
  + This means there is no guarantee that the devices belong
  + to a valid user of the room.
  + </p><p>
  + We recommend you go through the verification process
  + for each device before continuing, but you can resend
  + the message without verifying if you prefer.
  + </p>
  <p>Unknown devices:</p>
  <UnknownDeviceList devices={this.props.devices} />
  </div>
  