Django-tables2

- Fix issues for Python 2.6.4 -- thanks Steve Sapovits & brianmay
- Reduce Django 1.3 dependency to Table.as_html -- thanks brianmay

- Fix MANIFEST.in to include example templates, thanks TWAC.
- Upgrade django-attest to fix problem with tests on Django 1.3.1

- Fixed support for Django 1.4's paginator (thanks koledennix)
- Some juggling of internal implementation.
`TableData` now supports slicing and returns new `TableData` instances.
`BoundRows` now takes a single argument `data` (a `TableData` instance).
- Add support for `get_pagination` on `SingleTableMixin`.
- `SingleTableMixin` and `SingleTableView` are now importable directly from `django_tables2`.

- Renamed `BoundColumn.order_by` to `order_by_alias` and never returns `None`
(**Backwards incompatible**). Templates are affected if they use something like:

{% querystring table.prefixed_order_by_field=column.order_by.opposite|default:column.name %}

Which should be rewritten as:

{% querystring table.prefixed_order_by_field=column.order_by_alias.next %}

- Added `next` shortcut to `OrderBy` returned from `BoundColumn.order_by_alias`
- Added `OrderByTuple.get()`
- Deprecated `BoundColumn.sortable`, `Column.sortable`, `Table.sortable`,
`sortable` CSS class, `BoundColumns.itersortable`, `BoundColumns.sortable`; use `orderable` instead of `sortable`.
- Added `BoundColumn.is_ordered`
- Introduced concept of an `order by alias`, see glossary in the docs for details.

- Fix bug that caused an ordered column's `<th>` to have no HTML attributes.

- Updated example project to add `colspan` on footer cell so table border renders correctly in Webkit.
- Fix regression that caused 'sortable' class on <th>.
- `Table.__init__` no longer *always* calls `.order_by()` on QuerySets, fixes 55.
This does introduce a slight backwards incompatibility. `Table.order_by` now has the possibility of returning `None`, previously it would *always* return an `OrderByTuple`.
- `DeclarativeColumnsMetaclass.__new__` now uses `super()``
- Testing now requires pylint and Attest >=0.5.3