community/novnc: move from testing

I would like novnc in 3.19 because a Python major version upgrade is expected after that, and this aport depends on the websockify Python aport.

@vaka May i have websockify in community please? I have emailed you about taking over websockify (and a few other aports) on 27th November, but have not heard back until now. I would like to give you more time to think over that and respond, so have not taken over websockify in this MR, but merely moved it to community, as it is a dependency of novnc which i now maintain.

Update: 5 more days have passed, making it a total of 10 days since i emailed @vaka, so i'm adopting websockify.