Add stability message for Atom.io API

This indicates that the Atom.io API is not frozen - this is describing the state
of things, not announcing a new policy.
Upgrade to language-coffee-script@0.24
Use cross platform path in Project::replace spec
Upgrade to settings-view@0.131
Call signtool on Windows
:lipstick: Use switch
Use full path to signtool.bat
signtool is now on the PATH
Use JANKY_SIGNTOOL env var to sign
Always pass specs to test signing
Reenable specs
Add kill command for Windows
Kill all atom.exe before signing
Force kill on Windows
Temporarily disable specs
Break up commands into two spawns
Separate /F argument to taskkill
Publish builds from this branch to test signing
Comment out Janky check
Restore publish checks