Updates to the kernel messaging spec#388

Merged

SylvainCorlay merged 10 commits intojupyter:masterfrom

jasongrout:update

Jul 27, 2019

Commits on Jul 18, 2018

Commits on Jul 19, 2018

Fix control channel copy/paste error.
jasongrout
committed
Move shutdown request to its own section to emphasize the message is on the control channel.
jasongrout
committed
Percolate a control connection throughout the code.
jasongrout
committed

Commits on Jul 26, 2019

Revert status message updates to revert back to exactly three status message states.
jasongrout
committed