Add a form for entering new books

Create a form manually, to allow new books to be added to our database.
Note the cumbersome input for author_id; we'll fix that later ;)
Add trigger for logging

Amon2 doesn't have an equivalent of Catalyst's chained actions, but we
can simulate one via Class::Trigger (which Amon2 already pulls in, for
enabling dispatch triggers.)  Use it here in the controller to do some
logging via the Log::Minimal module.
Add a way to delete a book

Add our first take on a delete action for books.  This is deliberately
broken (we'll fix it later, see the original Catalyst tutorial doc about
this,) as this is more to build on the previous commit, implementing
chaining through triggers.
Fix dangerous URL left when deleting

Fix by redirecting to /books/list.  To supply our success message, pass
it via a query parameter.  Ugly, but works.
Remove Class::Trigger

At second glance, we really don't need Class::Trigger here for chaining
methods, as an Amon2 controller class is just a regular Perl class with
no inheritance from Amon2::Web (in fact, context is passed separately in
$c.)  So, just turn the triggers into proper (private) methods.
We HTML5 nao

Tweak the layout a bit to be more modern lol ;)
Update top navbar links

Just update with our /books links.
A bit of refactoring

Since we're calling Teng methods directly, change this by creating new
methods in BookList::DB that will serve as our API for the database.
This should allow, for example. changing from Teng to some other DBI
wrapper or ORM, and further separate concerns between the Books
controller and the database.
Clarify book object method

Rename _object to _book so we know that we're trying to get a book
object from the database.
Update SQLite schema

Split off the example data into its own file, that we can load
separately.  Also supple an ALTER TABLE schema for the books, to
accomodate creation and update timestamps.
Add a timestamp to the books for searching by creation/update time

Update the database so books get a couple new fields for creation and
update time, and consequently update the Teng class.  This allows us to
have a list_recent action that can search books by time created.

This makes us use the HTTP::Date module (pulled in by Amon2 deps.)
Add some more links to the layout

Link to our frequently-used actions for easier testing/illustration.
Add HTTP::Date to requirements

While Amon2 pulls in HTTP::Date indirectly, put it in our cpanfile just
in case.  Also update the snapshot.