Produce a more defensible HTML mail rendering of Remarkup blockquotes
Summary:
Ref T10694. Fixes T7031. We don't currently put any inline styles on <blockquote> tags produced by prefixing blocks with > in Remarkup.
Add some styles.
Test Plan:
Generated some reasonable mail with complex blockquote elements:
{F1260072}
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T7031, T10694
Differential Revision: https://secure.phabricator.com/D15855