blog: Remove unnecessary kwargs manipulation from custom_index.

I don't know if this code is left over from previous versions or what, but
it's not doing anything now. custom_index doesn't pass kwargs to anything
else, so there's no need to fiddle with the dict so much.

Add sitefundgoal to top level view context.

The base template now has access to the fund-raising goal that will be
displayed site-wide. The view here must provide it in the context for
access everywhere.

Furthermore, we need a local context processor to make sure it's in
context everywhere, and we have to make sure that context is properly
passed along.

This code is a bit cargo-culted in, based on what I read in various
places about adding the Request context.

Just quit it with this relative import stuff.

While I think these relative imports seem to be valid for the running
application, I am having trouble with the django-admin applications
regarding them. I don't see this syntactic sugar as absolutely
essential, so I'm just going to change it now.

Typo fix from last commit:

s/extra_content/extra_context/

More extra_context stuff? Put it all in there!

Simply move the blog_entries field into extra_context and pass the whole
darn thing along to the template.

Rework blog's custom_index for new pagination.

The pagination support changed, and as was previously done a few commits
ago for news, I'm trying a similar solution for blogs.

In this case, I'm trying to use the existing custom_index() method we
have and adapt it to properly support pagination in the way we want.

I'm not completely sure this will work, but I think it's at least close.

Adapted Django application stuff for Conservancy; and normalized to string
"conservancy" within code and templates.