fix alignment
remove empty example notebook

looks like it was committed by mistake
allow session_id to be undefined when starting kernel channels
use default kernel name in kernels service

matches sessions API
update font-awesome
genereate css
Merge pull request #6686 from minrk/default-kernel

use default kernel name in kernels service
Merge pull request #6684 from minrk/rm-spreadsheet

remove empty example notebook
remove redundant 'responsive-utilities' from style.less

it's already included in bootstrap.less
Merge pull request #6691 from minrk/rm-bs

remove redundant 'responsive-utilities' from style.less
Merge pull request #6685 from minrk/allow-no-session-id

allow session_id to be undefined when starting kernel channels
Merge pull request #6669 from SylvainCorlay/font_awesome_update

Font awesome update
Merge pull request #6681 from SylvainCorlay/widget_hbox_align

Minor change in widgets.less to fix alignment issue
support buffers in comm messages

- add buffers arg to comm Python api
- support binary websocket messages when buffers are present
- reimplement utf8 in javascript, because javascript is the best
s/unserialize/deserialize
use utf8.js

move message serialization to kernel.serialize module
support binary message from javascript
use TextEncoding for string<->ArrayBuffer

requires text-encoding js polyfill, for now
install text-encoding polyfill
test websocket-friendly binary message roundtrip

Python-side