Move parts of fauxton.less to templates.less

Fauxton.less is pretty hot code when you look at the commit
frequency. This commit just moves the parts of todays
fauxton.less to the new templates.less file to avoid a
long living branch with endless merge commits. This way
my colleagues can already use the new templates.less file
and have the advantage of a small separate template.less file
as soon as possible.

Based on the work of Jenn Schiffer <jenn@pancaketheorem.com>
(@jennschiffer) and Sue Lockwood <deathbear@apache.org>
(@deathbearbrown)