Create new home page look

This is the basic homepage look. The code is sloppy and the look won't
work with submissions that are images or submissions that start off with
a lot of non-viewable characters, but the basic idea has been conveyed.
Remove unneeded changes
Move some controller logic into "Homepage" object

This was mostly an intellectual exercise to attempt to follow Sandi
Metz's "one instantiation per controller action" rule. I've obviously
failed to follow that rule, even still. My reason:

`@publication` is assumed to be set in the layout, and short of
refactoring the whole site, it needs to be set.

As far as moving the other logic into a `Homepage` object, it seems to
have accomplished a few nice things:

* the logic for what the homepage needs is contained in one
  outside-the-Rails-stack, easy-to-test place (I'm not currently taking
  advantage of this)
* stubbing this new object to keep existing tests passing was easy
* the view cleanly declares what data certain sections are interested
  in, which is interesting. I'm not sure I care much, since html
  sections & ids already accomplished that.
Test drive the new home page with real data

And adjust accordingly. Lessons learned:

* The home page should only feature submissions from fully-published
  magazines; that is, magazines that have had a notification sent
* Truncating data that contains html tags is bad news
* Including all of the contents on the page & limiting the height with
  CSS is nbd
* Photographs looks really dumb if they're faded out (will need to deal
  with this more intelligently later, instead of just not including
  them)

The HookSubmission thus went away, which was nice.

The definition of @hook in lib/homepage is a little bit goofy, mainly
because during testing the publication may not have any published
magazines, and it needs to account for that. Someday, when people first
sign up for Publishist, this will also be the case, so the home page
really ought to account for a blank @hook.
Properly load home page when publication has no published magazines

Also, fix creation of new publications.
Merge pull request #9 from chadoh/homepages

Create new home page look for individual publications