chore(*): update CoreOS to 440.0.0

https://coreos.com/releases/#440.0.0
chore(*/systemd): remove deprecated X-Condition in fleet units
Merge pull request #1845 from carmstrong/remove_deprecated_condition

chore(*/systemd): remove deprecated X-Condition in fleet units
Merge pull request #1844 from carmstrong/coreos-440.0.0

chore(*): update CoreOS to 440.0.0
ref(cache): build Redis from source
docs(installing_deis): remove in-place upgrade documentation
Merge pull request #1852 from mboersma/fix-cache-image

ref(cache): build Redis from source
Update README.md

World's smallest docs typo fix.
Merge pull request #1860 from fmd/patch-1

Update README.md
Merge pull request #1854 from carmstrong/remove_upgrade_documentation

docs(installing_deis): remove in-place upgrade documentation