Supporting JVM/Ring installing in Virtualenv

Add code to support JVM/Ring installing in Virtualenv.

Test steps:
* virtualenv ENVHOME
* cd ENVHOME
* source bin/activate
* export UWSGI_PROFILE="pyring"
* pip install uwsgi
* check with path ENVHOME/bin , jvm_plugin.so and ring_plugin.so should be in this directory
* check with path ENVHOME/lib , uwsgi.jar should be in this directory