Refactor deprecated syntax

[simoebenhida]

The below syntax is deprecated and it doesn't also work on Safari 12.

pc.setRemoteDescription(sessionDescription, successCallback, errorCallback);

You can check it here: https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/setRemoteDescription

[jenkinskurento]

Hi there, thanks for your Pull Request!

A Kurento member needs to verify that this patch is reasonable to test. In case it is, they should write a comment with the phrase test this please. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by Kurento members will still work. Regular contributors can be whitelisted to skip this step.

[j1elo]

Closed by #32
(same fix applied)

Thanks!

[simoebenhida]

@j1elo It will be cool if you merge the old MRs first next time 😀

[j1elo]

Agree, sorry! I was asked to attend the other PR, so I focused my work on there.
Still, when fixing this I made sure to add both to the Thank You section of the next Release Notes. This PR did an important work in letting me know what was the minimal change needed to achieve the fix, so thanks!