Add captcha to comments

[lshep]

we would like a captcha on submitting a comment. held off given issue with "edit" of new post issue

[n1khilmane]

Notes:

• The codebase doesn't have the captcha form, need to add it seperately
• Need to figure out the template for adding the captcha
• forms.py / views.py for the respective directory (forum or accounts or etc) needs to be discovered
• test and integrate