Remove magic for loading templates from module names
Fix tests to use full template names
Remove duplicate traitlet definition
Drop unused traitlet imports
render custom HTML for error pages
catch pandoc failures in nbconvert handlers
add error page templates
add error css
allow notebook to start without nbconvert

catches import / key errors and turns them into proper http errors
Improve test for nbconvert citation filter.

'import lxml' was succeeding, but 'from lxml import html' was failing.
Fix EvalFormatter test for Python 3.4

Changes to string formatting mean slicing in EvalFormatter now works.
Improve Python 3 compatibility for example scripts.
Remove some out of date information about pandas DataFrame reprs
Improve Python 3 compatibility in example notebooks
Rerun BackgroundJobs example NB to save in new format, plus Py 3 fixes
Polish test notebook
Update parallel example notebooks for Python 3
Update some print statements in the docs
Set numpydoc options to produce fewer Sphinx warnings.

The second is a new option that my PR numpy/numpydoc#6 adds, so we
should wait until that is merged to merge this.
Add comment about string formatting changes in Python 3.4