add unformal Name for 1.0
unformal name -> codename
signature_scheme lives in Session

not ConnectionFileMixin
mention metadata / display_data similarity in pyout spec
remove pylab from notebook doc
update nbconvert doc

update to new CLI

remove documentation of ill-advised `--script` option.
new util that also passes back the returncode
test for get_output_error_code
updated tests to use get_output_error_code
allow for List traitlets to come from command line
all nbconvert tests pass with pandoc
the last set of pandoc-dependent test
move ipython command line logic to one place

it keeps getting repeated, more elegant to move it out into the call
rename nbconvert doc to nbconvert.rst
prevent profile_dir from being undefined

can happen when other traits are configured that depend on profile_dir,
e.g. `NotebookApp.extra_static_paths`.

This ensures that `init_profile_dir` fires prior to any reference
to the profile directory.
add some detail in rst and markdown output
add pandoc note
update payload source

should be simple key, not Python (or worse, IPython) specific long key.

I could have sworn I did this long ago,
but apparently the source key was only updated in display_data,
not execute_reply.
test KernelManager.get_connection_info
maintain instances of exporters for use in export_by_name

avoids recreating new Exporters every time