implement comment feature for activities

[Wenxiu332]

create comment model, add comment box, add template for viewing comments for activities

[CLAassistant]

All committers have signed the CLA.

[brylie]

Thanks :-) Could you also attach a screenshot of the activity discussions to this PR description?

[brylie]

@Wenxiu332, could you post a screen grab of the Companionship Care UI showing an activity discussion? I.e., a picture of the code you are working on as it renders in the Companionship Care user interface.

[Wenxiu332]

sure, here's "add comment" button on the circle_activity.html page and the comment_detail.html page for a particular activity once user click "view comment"

[Wenxiu332]

@brylie hi, is there any other modifications you need from me?

[brylie]

@Wenxiu332, no further commits are needed. I will do some design work to communicate how the discussion feature should work. Thanks for your contribution so far :-)