added the version number for Java8 class files

.gitignore

 .DS_Store
 .classpath
 .project
+.settings
 TestLog.xml
 

src/main/javassist/bytecode/ClassFile.java

      */
     public static final int JAVA_7 = 51;
 
+    /**
+     * The major version number of class files
+     * for JDK 1.8.
+     */
+    public static final int JAVA_8 = 52;
+
     /**
      * The major version number of class files created
      * from scratch.  The default value is 47 (JDK 1.3).