Use v4 for blubber 0.8.0

Bump helm chart version for limitconfig causing failing "helm test".

Change-Id: I850990920748ad80b59093d188a529ae916dc3f2

Work on Go Modules has been moving steadily with basic support in 1.11
and more mature support in the recently released 1.12. Eventually we
should look at using it for dependency management (away from `dep`) but
let's start by simply declaring the package name in a new `go.mod` to
allow building of our project outside the hell that is `GOPATH`.

Change-Id: I90b9f35194afe5538dce8db67b2b7c2d551bfaff

Add dependencies, gcc, git, and make, needed to build and test blubber.
These added depedencies were already present in the dockerhub
golang:1.10-stretch base image, but must be installed on top of the
leaner wmf golang:1.11.5-1 base image.

Change-Id: I75a3263b2e4635ed21a393531d901dcb9620453a

Uses the github.com/ghodss/yaml library to convert YAML to JSON before
unmarshaling for the purposes of supporting YAML and JSON input while
converting to only support JSON internally.

Bug: T207694
Change-Id: I00668014907e9ea54917f5d5067cac08d0668053

Change-Id: I726094fd9afa593df31425c86060c4f1d52d8b83

See https://github.com/golang/lint/issues/415

Change-Id: Ic6d5c90b1409ba1799cfcd5000f7fc1798423e59

Change-Id: I29e0b16f17af572c02c68418e153e26b8e21fa81

Added a `blubber.yaml` that defines a single test variant and entry
point for use with the new generic `blubber-test` CI job (see
I31b367f2ab8b897fa988e70222f70d84186a631b).

Bug: T200452
Change-Id: I60b23e1bca8486e43ebf0f62198e85833f86b921