Set a default for Passenger's maximum pool size.

Previously, we didn't set a default, which made development deployments
of the CAS server fail.
Set up Apache access log.  #2702.

I'm using a single access log because

1. we have multiple vhosts, each running their own application
2. inter-application communication is common
3. because of (1) and (2), I think it's useful to see all access events
   in the same log stream
4. tagging each message with the vhost and sending it to the same stream
   is the easiest way to pull that off

This adds a few dozen unnecessary extra characters for the CAS log, but
those can be taken care of with i.e. cut.