Move md-cell display logic to css
remove useless comment
update to warnings
Update path.py

change str formatting to repr representation.
Handle 'deletable' cell metadata
Add tests for undeletable cells
Make cell be undeletable ONLY when metadata is explicitly false
Fix tests
Properly mock winreg functions for test

Fixes a lot of test failures on Python 3.4 on Windows, caused by
importlib trying to use our mocked out winreg functions when
reload(path) was called.
put back null gui hook for osx

`--gui osx` doesn't make sense on its own,
but it's called by `--matplotlib osx`,
which does.
add MultiKernelManager.default_kernel_name configurable

sets the kernel name to use, if unspecified
allow kernel_name to be undefined in requests

fallback to KM.default_kernel_name in that case
allow kernel_name to be undefined in js

Falls back to KM.default_kernel_name,
as configured server-side.
drop some 2.6 hacks
drop more 2.6 hacks
remove unused dateformat

we are using moment.js for dates now
Merge pull request #6579 from minrk/rm-dateformat

remove unused dateformat library
Merge pull request #6568 from minrk/remember-kernel

Make default kernel configurable
Merge pull request #6555 from minrk/put-back-osx

put back null gui hook for osx
Merge pull request #6528 from jgors/master

update to warnings