changing comment form input to a button so we're able to change the display...

changing comment form input to a button so we're able to change the display text + adding comment form title

opentech/apply/activity/templates/activity/include/comment_form.html

-<form method="post" id="comment-form">
+<h4>Add communication</h4>
+<form class="form form--comments" method="post" id="comment-form">
     {% csrf_token %}
     {{ comment_form }}
-    <input id="comment-form-submit" name="form-submitted" type="submit" form="comment-form" value="Comment">
+    <button id="comment-form-submit" name="form-submitted" form="comment-form" class="button button--primary" type="submit" value="comment">Add message</button>
 </form>