AS7-6570 fixes for buiding on JDK7

* upgrade javassist to support jdk7
* upgrade & mockito & powermock to support jdk7
* upgrade junit to 4.11 to gain test ordering support
* fix test ordering

This PR just updates few dependencies and fixes few tests to make it pass also on JDK7.
It does **not** add JDK7 requirement for building!

this will enable us to gradually migrate to JDK7.