* Add golangci-lint as linting tool
* Disable failing staticchecks to start; GitHub issue to handle coming soon
* Run `goimports -w` to repair all source files that have improperly
formatted imports
* makefile: Add ci-lint target to run on travis
This change adds a new make target for running golangci-lint on newly
added Go files only. This target is expected to run during Packer ci builds.
* .github/contributing: Add code linting instructions
* travis: Update job configuration to run parallel builds
Run now takes a context as well as a statebag. We'll assign the context
to the blank identifier to prevent namespace collisions. We'll let the
step authors opt-in to using the context.
`find . -iname "step_*.go" -exec gsed -i'' 's/func \(.*\)Run(/func \1Run(_ context.Context, /' {} \;`