(SERVER-85) Sync CA CRL to Host CRL at startup

This commit changes the master to, at each startup, copy the file
pointed at by the Puppet `cacrl` setting, if it exists, over to the
file pointed at by the Puppet `hostcrl` setting.

This commit also changes the `override-webserver-setting!` logic to
use the file at the `hostcrl` setting rather than the one at the `cacrl`
setting to determine which file the webserver uses to validate
certificates for connecting clients.  This was done based on the fact
that a "standalone" master -- one hosted without a corresponding active
CA in the same container -- would have used the `hostcrl` setting under
the Ruby master.  With the logic in place to copy the `cacrl` to the
`hostcrl` when a real CA is in place, the latest CRL, when the master
and CA are running in the same container, should now be in place at
service startup.
I'll weigh in on this sometime after we've wrapped up 1.0 changes.