Add static prefix in randomized ipv6.

src/fr/devinsy/logar/app/anonymizer/Ipv6Generator.java

@@ -61,6 +61,18 @@ public final class Ipv6Generator
                 {
                     buffer.append(c);
                 }
+                else if (index == 0)
+                {
+                    buffer.append('b');
+                }
+                else if (index == 1)
+                {
+                    buffer.append('a');
+                }
+                else if (index == 2)
+                {
+                    buffer.append('d');
+                }
                 else
                 {
                     buffer.append(RandomStringUtils.random(1, "0123456789abcdef"));