Provide a general Java API which will provide a way to inject Byteman agent to current JVM

Currently there is no provided Java API which could be used by libraries (e.g. `contrib` ones) to inject Byteman agent to running java process. As user you can use `bminstall` script to do so. It would be good to have a way to do it from Java API and then provide a way an to easily install the agent to the current JVM - this is thing which `BMUnit` already implements but it does not provide it as general utility usable for other libraries.

The task is rethink the way the general approach and later think about use of this in `dtest` library to have easy way to inject byteman agent to the JVM of running tests.