Minor admin template tweaks

[Jared Ahern]

Hello!

New contributor here (at least I hope to be). I had two small tweaks to the admin templates that I wanted to run by people here:

1) I added a block within the breadcrumbs around the initial "Home" part, and adjusted all the templates such that a user could override this new block once in base_site.html and replace "Home" with something else. For example, in my case, I'd like to make it more like "Site > Admin", with links. Right now, this appears to require extending all of the templates. See commit.

2) I could be wrong, but it doesn't seem like there's a direct way to add content between the header and the breadcrumbs. In my case, I've provided a drop-down menu bar there, by overriding base.html. However, it would be better if I could leave base.html untouched, and just extend base_site.html. So I added an empty block at that location in base.html. See commit.

Would either or both of these be acceptable for PRs? Would I need docs/tests/tickets?

Regards,

Jared