Prepare for release (#37)

* Prepare for release

Added LICENSE, set version and configured GoReleaser/Docker

* Updated LICENSE

internal/version/version.go

@@ -0,0 +1,33 @@
+package version
+
+import (
+	"fmt"
+	goversion "github.com/hashicorp/go-version"
+	"runtime/debug"
+)
+
+var (
+	Version     = "unknown"
+	Commit      = "unknown"
+	FullVersion = ""
+)
+
+//nolint:gochecknoinits
+func init() {
+	if Version == "unknown" {
+		info, ok := debug.ReadBuildInfo()
+		if ok {
+			// We parse the version here for two reasons:
+			// * to weed out the "(devel)" version and fallback to "unknown" instead
+			//   (see https://github.com/golang/go/issues/29228 for details on when this might happen)
+			// * to remove the "v" prefix from the BuildInfo's version (e.g. "v0.7.0") and thus be consistent
+			//   with the binary builds, where the version string would be "0.7.0" instead
+			semver, err := goversion.NewSemver(info.Main.Version)
+			if err == nil {
+				Version = semver.String()
+			}
+		}
+	}
+
+	FullVersion = fmt.Sprintf("%s-%s", Version, Commit)
+}