Experience Composer API enhancements

[manchuck]

What is this PR doing?

Adding the render

How should this be manually tested?

opentok.listRenders({}, (err, renders) => {
    if (err) {
        console.log("There was an error")
        console.log(err);
        return;
    }

    console.log(renders);
})

opentok.getRender('<render id>', (err, render) => {
    if (err) {
        console.log("There was an error")
        console.log(err);
        return;
    }

    console.log(render);
})

opentok.startRender(
    {
        sessionId: sessionId,
        token: token,
        url: '<callback url>',
    }, 
    (err, render) => {
        if (err) {
            console.log("There was an error")
            console.log(err);
            return;
        }

        console.log(render);
    }
)

opentok.stopRender('<render id>', (err, render) => {
    if (err) {
        console.log("There was an error")
        console.log(err);
        return;
    }

    console.log(render);
})

What are the relevant tickets?

DEVX-6495

[manchuck]

This is going to need #282 to be closed before moving forward

[jeffswartz]

Please rev the version number. If this will be bundled with other enhancements, please target the dev branch.

[hamzanasir]

Other than adding the docs that @jeffswartz commented it looks good to me!