Sets limit to comment indents | 5th level

[robert9g]

Fixes #1088 .

Changes:

• added CSS class Comment__replies--never-indent
• put that class in comments starting with 5th level
• removed @media @small from .Comment__text so that comment avatars would show up after 5th level
• updated the hardcoded .Comment__replies--no-indent margin to use the @comment-text-offset-small var

Observations:
I know that there were issues between the comment avatars (#883) and the code blocks (#771), and removing overflow:hidden; was needed to properly render code block. But this should be fixed because we calculate the width for each .Comment__text element.

I tested on these pages:

• has a lot of code comments: /test/@hellosteem/5ihr1p-test#@hellosteem/re-hellosteem-5ihr1p-test-20171018t132820462z
• has a lot of replies: /cesky/@bucipuci/narocna-kapca-challenge-captcha
• has the @minnowpond comment with the code element in it: /philosophy/@michellecarter/what-is-the-highest-power

[jm90m]

working well for me, maybe @bonustrack can take a final look since he seems to catch lots of random cases

[bonustrack]

Looking good