Fix issue with looking up child pages.

The first issue described in #25 is now fixed by overriding the
``get_children`` method of the ``FancyPage`` model. Instead of returning
the underlying ``PageNode`` queryset, it now uses this queryset to
retrieve the corresponding ``FancyPage`` queryset.

Resolves #25.
Fix moving pages through API.

Moving pages using fancypages' internal API had a few issues introduced
by the recent refactoring. It is now ensured that the JS code is using
the UUID rather than the PK of the page. In addition, creating
containers ignored the language code currently set in the request cycle
and would attempt to create containers without a proper language code
which caused additional errors. Both issues are now resolved.

Resolves #25.
Remove unused static dirs to prevent debug toolbar from failing in sandboxes
Remove TransactionMiddleware from sandbox
Just some minor cleanup.
Add docs target to make file in project root