ref(builder): compress archive into tarball

When we removed pigz from slugbuilder, it changed the format to a
tar file. Compressing it with gzip by supplying tar the -z option
reverts this behaviour.
feat(deisctl): check for required configuration on platform install
docs(*): set required platform config before install/start
Merge pull request #2245 from gabrtv/fix-deisctl-docs

docs(*): set required platform config before install/start
Merge pull request #2244 from gabrtv/deisctl-required-keys

feat(deisctl): check for required configuration on platform install
Merge pull request #2218 from bacongobbler/tarball

ref(builder): compress archive into tarball
chore(release): update version to v0.14.1
Merge pull request #2247 from mboersma/release-v0.14.1

chore(release): update version to v0.14.1
chore(release): update version in master to v0.14.1+git
docs(README.md): remove instructions for placing apps on a different cluster
Merge pull request #2250 from mave/dev

docs(README.md): remove instructions for placing apps on a different cluster
Merge pull request #2249 from mboersma/bump-v0141+git

chore(release): update version in master to v0.14.1+git
ref(user-data): "make discovery-url" copies from user-data.example

This also adds contrib/coreos/user-data to .gitignore, so that local
changes to this essential file do not cause "git status" to mark the
repo as dirty.