fix alignment
allow session_id to be undefined when starting kernel channels
update font-awesome
genereate css
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
install local mathjax on Travis

when running the js tests

I'm not sure why loading MathJax from the CDN is falling on Travis,
but it's not happening locally.
Merge pull request #6703 from minrk/install-mathjax-travis

install local mathjax on Travis
Add REST API for retrieving, storing and updating config
Fix docstring, validate JSON on PUT
Use jsonpatch for modifying config
Add jsonpatch to Travis install instructions

Replacing jsonpointer, which we no longer use
Fix another docstring