- add -html5 option for javadoc under java9+
- integration-test.sh use java 10 build

- use thread kotlin function
- protected for finalize method

- use CtClass.getDeclaredMethod(String, CtClass[])
  instead of CtClass.getDeclaredMethod(String)
- javadoc of CtClass.getDeclaredMethod(String):
  If there are multiple methods with the specified name,
  then this method returns one of them.

- add contributor @xwshiustc

timestamp INFO [thread name] class-name: message info

java agent start and process when app boot,
it is difficult to use (java.util.logging)JUL correctly 😩;
especially cooperate with app server(eg tomcat or jboss).

use simply std out/error instead of JUL.

more info see #97

more discussion see #95

- build by java 8 with java 6 source/target
    - full functions with java 8 support(ForkJoinPoolTest)
    - support java 6
- Travis ci has multiple java version: java 6/7/8/9
- scripts and test case/demo cleanup