Mandyville::Database needs to be pre-declared, otherwise DESTROY is called too early

[owendavies93]

Mandyville::Database needs to be used like this:

my $db = Mandyville::Database->new;
my $countries = Mandyville::Countries->new({
    dbh  => $db->rw_db_handle(),
    sqla => SQL::Abstract::More->new,
}); 

If you use it in a more succinct way:

my $countries = Mandyville::Countries->new({
    dbh  => Mandyville::Database->new->rw_db_handle(),
    sqla => SQL::Abstract::More->new,
}); 

The handle gets DESTROYed too early, and you get errors like:

DBD::Pg::db selectrow_array failed: Cannot call execute on a disconnected database handle

It'd be nice if you didn't have to pre-declare the database object, although in practice it may never be a problem.