On Android/Chrome using camera failed with : Failed to execute 'play' on 'HTMLMediaElement': API can only be initiated by a user gesture.

Hi,

i try to use the camera on smartphone (android + chrome) and since few days i always have :

```
Failed to execute 'play' on 'HTMLMediaElement': API can only be initiated by a user gesture.
```

If i look at the package, the play() action is done on Template rendered, maybe it's the problem because the action is not triggered by user.

To reproduce:
- just add the mdg:camera
- render the template "camera" using {{> camera}} in your layout
- start an nginx as a proxy with SSL (because getUserMedia no more works without SSL)
- start meteor app
- open Chrome on your Android device
- fill the url of your computer
- The video stream is not displayed, but you only have a photo

Reproduce the issue with mdg:camera, the “camera” template, an SSL nginx proxy, and Chrome on Android. Inspect where the template invokes HTMLMediaElement.play(), then verify that the camera video stream is displayed rather than only a photo.

Written by the indexing model from the issue text.