nicetrans: Only emit local-candidate after gathering
nicetrans: Only emit local-candidate after gathering

Unfortunately libnice doesn't currently support doing connectivity
checks untill it has finished gathering. If we send a remote peer our
candidates before finishing gathering they can start sending us
connectivity checks before we're ready for them...

So instead sends the local candidates in one batch when gathering is
finished, so we'll be ready for the connectivity checks.

pexip/farstream,shadeslayer/farstream,shadeslayer/farstream,pexip/farstream,kakaroto/farstream,tieto/farstream,pexip/farstream,shadeslayer/farstream,tieto/farstream,tieto/farstream,kakaroto/farstream,kakaroto/farstream,tieto/farstream,pexip/farstream,tieto/farstream,kakaroto/farstream,shadeslayer/farstream