Add an appendix

For the inclusion of js libraries or general html elements outside the scope
of flowtime, we can pass a performatted html string.

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Output jade error messages

This saves you alot of time, when you are on a plane and cannot
figure out about which syntax error jade complains this time...

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Close outermost div and move appendix behind it

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>