Install Compass in virtual env

Create virtualenv for compass, point compass site packages to virtualenv,
make virtualenv accessable for apache.
Change compass executable scripts to use python in env to be virtualenv
compatible.
Make progress_update daemon use virtualenv.
Comment out some health checks that use packages not available to pip, eg,
yum, apt since we have other ways to check packages any way.

Change-Id: Ib48633601bf238ffc660c4694834897edbe45e07
Merge "Install Compass in virtual env"