Fixes up QuoteSpan formatting in the comment detail view.

Now uses `HtmlUtils.fromHtml` to use a `WPQuoteSpan` which has a better block quote line and text color.
Code style fix.
Removed unused imports
Merge pull request #1580 from wordpress-mobile/issue/1572-blockquote-st

Fixes up QuoteSpan formatting in the comment detail view.
Merge branch 'develop' of https://github.com/wordpress-mobile/WordPress-Android into issue/1491-reader-block-blog