add go.mod cataloger (#97)

integration/fixture_pkg_coverage_test.go

@@ -133,6 +133,14 @@ var cases = []struct {
 			"unicorn":              "4.8.3",
 		},
 	},
+	{
+		name:        "find golang modules",
+		pkgType:     pkg.GoModulePkg,
+		pkgLanguage: pkg.Go,
+		pkgInfo: map[string]string{
+			"github.com/bmatcuk/doublestar": "v1.3.1",
+		},
+	},
 }
 
 func TestPkgCoverageImage(t *testing.T) {

integration/test-fixtures/image-pkg-coverage/go/go.mod

@@ -0,0 +1,7 @@
+module github.com/anchore/imgbom
+
+go 1.14
+
+require (
+	github.com/bmatcuk/doublestar v1.3.1
+)