Implementing generic parser plugins and documentation

This constitutes a large change in how we will parse different data
formats going forward (for the plugins that support it)

This is working off @henrypfhu's changes.

plugins/outputs/graphite/graphite_test.go

@@ -71,16 +71,11 @@ func TestGraphiteOK(t *testing.T) {
 	// Start TCP server
 	wg.Add(1)
 	go TCPServer(t, &wg)
-	wg.Wait()
-	// Connect
-	wg.Add(1)
 	err1 := g.Connect()
-	wg.Wait()
 	require.NoError(t, err1)
 	// Send Data
 	err2 := g.Write(metrics)
 	require.NoError(t, err2)
-	wg.Add(1)
 	// Waiting TCPserver
 	wg.Wait()
 	g.Close()
@@ -88,9 +83,8 @@ func TestGraphiteOK(t *testing.T) {
 
 func TCPServer(t *testing.T, wg *sync.WaitGroup) {
 	tcpServer, _ := net.Listen("tcp", "127.0.0.1:2003")
-	wg.Done()
+	defer wg.Done()
 	conn, _ := tcpServer.Accept()
-	wg.Done()
 	reader := bufio.NewReader(conn)
 	tp := textproto.NewReader(reader)
 	data1, _ := tp.ReadLine()
@@ -100,7 +94,6 @@ func TCPServer(t *testing.T, wg *sync.WaitGroup) {
 	data3, _ := tp.ReadLine()
 	assert.Equal(t, "my.prefix.192_168_0_1.my_measurement.value 3.14 1289430000", data3)
 	conn.Close()
-	wg.Done()
 }
 
 func TestGraphiteTags(t *testing.T) {