Support for Echo360 Videos in H5P

[echo360-damyon]

At Echo360 (https://echo360.com/) we have been asked by our customers to allow videos captured in our EchoVideo platform to be able to be included in H5P content. We have added these features in our test environment and we intend to release them generally at the end of the year.

For this feature to be implemented it will require small changes h5p-video and the h5p-editor-php-library inline with the other supported video platforms.

[echo360-damyon]

There are 2 open pull requests to implement this feature:

#90

and

h5p/h5p-editor-php-library#182