4237 [camera_web] Update the web plugin README (cla: yes, p: camera, platform-web)

4239 [camera_web] Add support for pausing and resuming the camera preview (cla: yes, p: camera, platform-web)

4240 [camera] Add web support (cla: yes, p: camera, platform-web)

4241 [video_player] removed video player is not functional on ios simulators warning (cla: yes, waiting for tree to go green, p: video_player)