_s: Simplify author template.

Set up author data for the author template immediately, rather than
waiting for the first the_post() call.
This removes the need to call the_post() and rewind_posts() in an
author template to print information about the author.

Fixes #346.
removing uneeded CSS declaration, adding a note, and reordering some declarations

originally submitted here:
https://github.com/richardmtl/_s/commit/5d15eef59b838200cd255bea6d954064
e87cf3cf ; additional note and explanation found there
Merge pull request #365 from richardmtl/master

_s: Remove unneeded CSS declaration, and document vendor prefixes.