Added basic Subsonic interface

app/src/main/java/com/cappielloantonio/play/subsonic/utils/StringUtil.java

@@ -0,0 +1,28 @@
+package com.cappielloantonio.play.subsonic.utils;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+public class StringUtil {
+    public static String tokenize(String s) {
+        final String MD5 = "MD5";
+        try {
+            MessageDigest digest = java.security.MessageDigest.getInstance(MD5);
+            digest.update(s.getBytes());
+            byte messageDigest[] = digest.digest();
+
+            StringBuilder hexString = new StringBuilder();
+            for (byte aMessageDigest : messageDigest) {
+                String h = Integer.toHexString(0xFF & aMessageDigest);
+                while (h.length() < 2) {
+                    h = "0" + h;
+                }
+                hexString.append(h);
+            }
+            return hexString.toString();
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+        }
+        return "";
+    }
+}