feat(refacto): move everything in internal package

This allows to install katenary with `go install` and to clean up the
project folder.

internal/generator/version_test.go

@@ -0,0 +1,34 @@
+package generator
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestVersion(t *testing.T) {
+	// we build on "devel" branch
+	v := GetVersion()
+	// by default, the version comes from build info and it's a development version
+	if !strings.Contains(v, "(devel)") {
+		t.Errorf("Expected version to be set, got %s", v)
+	}
+
+	// now, imagine we are on a release branch
+	Version = "1.0.0"
+	v = GetVersion()
+	if !strings.Contains(v, "1.0.0") {
+		t.Errorf("Expected version to be set, got %s", v)
+	}
+	// now, imagine we are on v1.0.0
+	Version = "v1.0.0"
+	v = GetVersion()
+	if !strings.Contains(v, "v1.0.0") {
+		t.Errorf("Expected version to be set, got %s", v)
+	}
+	// we can also compile a release branch
+	Version = "release-1.0.0"
+	v = GetVersion()
+	if !strings.Contains(v, "release-1.0.0") {
+		t.Errorf("Expected version to be set, got %s", v)
+	}
+}