Update README for airgap documentation

Add more details about using HelmChart resource

Fix installer shasum check

Airgap image checksums may accidentaly be used by the installer, be
more specific to grep only for the downloaded executable.

Update vendor

Kubelet resolv.conf DNS update

Allow the kubelet resolv-conf flag to be set, or automatically
discovered from /etc/resolv.conf & /run/systemd/resolve/resolv.conf if
no loopback devices are present, or create our own which points to
nameserver 8.8.8.8

Upgrade to golangci-lint & go v1.12.1

Add tls-san flag

Skip writing manifest when using `--no-deploy`

Re-enable build validation

Instead of skipping the manifest when listing the directory, we now skip
creating it in the first place. This allows users to deploy manifests
that replaces the ones bundled, without having to come up with a new
name.

Fixes #230.

Adjust the startup order of docker-compose

Fix go get golang.org/x/* packages timed out issue.

* Set the selinux context

Generate air-gap image artifacts

Generate airgap artifacts from an images list for each architecture.

PullAlways ImagePullPolicy causes issues with offline/airgap support,
so only pull if image is not already present.

Fix version for cli

Air-gap chart support

Include static Helm assets in the build process needed for air-gap

Update docker-compose for v0.2.0, add agent docker-compose, update re…

Provide a static assets route for use with helm or other air-gap needs.