Added code to prevent print page breaks in cells, output_wrapper, and output.
put Running tab on the page
minimal KernelList
Moved widget files into static/widgets/*

Since they do not depend on anything ntoebook related
Updated require references to point to new files
add @onlyif_any_cmd_exists

like @onlyif_cmds_exist, but pass if any is available instead of all
run html nbconvert tests if node or pandoc is available
inconsequential cleanup pass on test_nbconvertapp
suppress warnings test_pandoc
capture logging in a few tests

this could probably be made more general,
but these were the two places I noticed log output.
install nodejs on travis
catch_warnings(record=True)

record is keyword only on Python 3
ok, Running tab is working now
fix typo in method name
refresh of Notebook list should reload sessions
don't double-join the notebook path
remove reiterated repetitively redundant "actively"
fixup positional arg parsing in notebook app

- `ipnb .` triggers override of sub-config, even when the parent isn't changed
- `ipnb /path/nb.ipynb` sets notebook_dir to `/path`
write config instead of direct assignment from the command-line

Gross.
Changed children list to CTuple.

Also removed some unused refences in the widget code
and added support for tuples in the pack/unpack code.