This makes it easier for user who want to theme but
don't have the ability to know how to customize templates
all that is required is a change in a config option
The reason why I chose the DEFAULT_THEME as variable,
as perhaps in the future we will allow users to chose their
theme whon logged in just like we do with languages
These templates add content to the top navbar
and to the repository page.
This way we do not have to copy and modify the whole
template, and re-modify it after upgrading Gitea if
it changes.
Signed-off-by: Alberto González Palomo <bugs@sentido-labs.com>