Fixed issue #771.Comment allow new line.

Raising Fresh PR on issue #771 as my previous branch got messed up while pushing from local.
I have tested all scenarios from my end. 
The comment div is taking care of next line.
In case of edit it accepts new line and on hitting enter it goes to next line. to post the changed comments user will follow same ctrl+enter.
It's not necessary, because a PR is really just a diff between forks/branches.  So it doesn't matter how many commits there are: only the final changes will be shown.  But you're welcome to.