Install the agent lib to non arch specific directory

https://fedorahosted.org/fesco/ticket/961
Update the spec file

- install the agent to _jvmlibdir because Java is not multi-lib
- do not require particular java devel package as the agent works with
the most common Java versions (1.6, 1.7, 1.8)

Thanks Mikolaj Izdebski and Jiri Vanek!