Added explicit error message for missing configuration arguments.
noteboook with spaces.ipynb test
updated test for spaces in filename
use notebook which has an image in it for the test
use grffile to support notebooks with spaces
add grffile to the basic latex template
added check_for_tornado, closes #3916

This way, those relying on the output of `python setup.py install` get
clued in about the fact that it is required for the notebook
Merge pull request #3918 from ivanov/fix-3916

added check_for_tornado

closes #3916
Merge pull request #3913 from ivanov/alt-fix-3774

use grffile to support spaces in notebook names

closes #3774
closes #3898
Merge pull request #3910 from dhirschfeld/config-error

Added explicit error message for bad connection files.
Fix, don't try to create '' directories
Make sure that a notebook_name is provided if writing to the filesystem
Allow for files output without an extension
Fixed call to pretty print.
pprint is the import function, not module
Fixed output to match other print statements
Fixed, should only be called if enabled
figure renamed to output
s/a/an
FIX Coalesce streams transformer, missing assignment to `last`
s/AttributeError/TypeError