Adding --annotation-ttl for automatic unlock

replay changes from #127

add Github Action to check links

Update for 1.4.0 release

Revert parts of #127, move to client-go/kubectl 1.17

	Tested on minikube with k8s 1.16.8, 1.17.4, 1.18.1

	After the release of kured 1.4.0 we should be able to go back.

	This was decided in our meeting
(https://docs.google.com/document/d/1bsHTjHhqaaZ7yJnXF6W8c89UB_yn-OoSZEmDnIP34n8/edit#heading=h.8cgszb6vuhza)

	Let's go with supporting 1.1[678] in this release.

print the node id when commanding a reboot

Unpin base docker image

The upside is that image building will always use the latest
stable version of the alpine OS, which might include security fixes.
The downside is that it's less reproducible, because the full
version isn't given.

While this commit isn't necessary per se, it's nice to have
an image that will be up to date, when we'll build it.

Update Go version to 1.13

	New Go image is recommended in https://circleci.com/docs/2.0/circleci-images/

	fixes: #129

Update to match k8s 1.18.0

	confirmed by running https://github.com/kubernetes-sigs/clientgofix

	closes: #123

	go get k8s.io/client-go@kubernetes-1.18.0
	go mod tidy

add information about monthly meetings

point to kured Slack

Keeping alpine fresh

Updating alpine to the latest version.
Tested this version of alpine and running fine, keeping versions of dependencies up to date.

Prepare 1.3.0 release

	Also point out how to create the dockerhub.yaml file,
	update other release related instructions.

	closes: #97

Use newer version of k8s client tools

add development docs

update to client-go as well