Consider to add `today` logic into `gchat.js#planRelease()`

[artembilan]

I have Bash logic like:

          if [ $dueDate = $(date '+%F') ]
          then
            dueDate=today
          else
            dueDate="on $(date -d $dueDate '+%B %d')"
          fi

Which I find as nice human-friendly feature.

I might be wrong, though, when all those -planning messages are parsed by some tool which can deal only with dates.
Then this issue can be closed and I'll revise my logic in favor of machine-friendly variant instead.

Thanks