more tolerent conversion jsontosdp

[mpromonet]

Hi,

Please find these 2 little modification that accept to convert from JSON to SDP:

• when a group is defined but has not content
• consider datachanel when media is "application" and applciationtype="rtp"

I made these modifications in order to convert to SDP a session-initiate send by jitsi.

Best Regards,
Michel.

[xdumaine]

Looks good to me, but could you add tests for this? @legastero @fippo do you see any problems with this?

[fippo]

how does the session-initate look like? A group without contents smells buggy but 👍 on being more robust

[mpromonet]

Maybe I do something wrong, but in my test the session-initiate always contains :

 "groups":[{"semantics":"BUNDLE"}]