Split the G401 rule into two separate ones

Now the G401 rule is split into hashing and encryption algorithms.

G401 is responsible for checking the usage of MD5 and SHA1, with corresponding CWE of 328.
And G405(New rule) is responsible for checking the usege of DES and RC4, with corresponding CWE of 327.

call_list_test.go

@@ -94,6 +94,32 @@ var _ = Describe("Call List", func() {
 		Expect(matched).Should(Equal(1))
 	})
 
+	It("should match a package call expression", func() {
+		// Create file to be scanned
+		pkg := testutils.NewTestPackage()
+		defer pkg.Close()
+		pkg.AddFile("cipher.go", testutils.SampleCodeG405[0].Code[0])
+
+		ctx := pkg.CreateContext("cipher.go")
+
+		// Search for des.NewCipher()
+		calls.Add("crypto/des", "NewCipher")
+
+		// Stub out visitor and count number of matched call expr
+		matched := 0
+		v := testutils.NewMockVisitor()
+		v.Context = ctx
+		v.Callback = func(n ast.Node, ctx *gosec.Context) bool {
+			if _, ok := n.(*ast.CallExpr); ok && calls.ContainsPkgCallExpr(n, ctx, false) != nil {
+				matched++
+			}
+			return true
+		}
+		ast.Walk(v, ctx.Root)
+		Expect(matched).Should(Equal(1))
+	})
+
+
 	It("should match a call expression", func() {
 		// Create file to be scanned
 		pkg := testutils.NewTestPackage()