Handle big images and videos in the app

If an image or video has a higher width than the device's width, it overflows horizontally and the user isn't able to scroll, so some content is not viewable. We have two choices:

• Let the Moodle users (the ones adding the media) to be responsible of handling this. Most users don't know CSS, so I don't think this is the right choice.
• Handle this in the app. An image can be adapted to screen width using these styles:

  max-width: 100%;

  height: auto;

We could create a directive (or add another attribute to format-text) that looks for images, videos and so and adds them a class to apply those styles.