cli: Add initial cli implementation.

- Add kata-runtime
- Add unit test
- Add Makefile to build cli

Fixes: #33

Signed-off-by: Julio Montes <julio.montes@intel.com>
Signed-off-by: James O. D. Hunt <james.o.hunt@intel.com>
Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>

cli/exit_test.go

@@ -0,0 +1,51 @@
+// Copyright (c) 2017 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var testFoo string
+
+func testFunc() {
+	testFoo = "bar"
+}
+
+func TestExit(t *testing.T) {
+	assert := assert.New(t)
+
+	var testExitStatus int
+	exitFunc = func(status int) {
+		testExitStatus = status
+	}
+
+	defer func() {
+		exitFunc = os.Exit
+	}()
+
+	// test with no atexit functions added.
+	exit(1)
+	assert.Equal(testExitStatus, 1)
+
+	// test with a function added to the atexit list.
+	atexit(testFunc)
+	exit(0)
+	assert.Equal(testFoo, "bar")
+	assert.Equal(testExitStatus, 0)
+}