Add mod_access_compat for Apache 2.2 style configs

Apache 2.4 has migrated from mod_access to mod_authz_host but provides
mod_access_compat to support configuration files using the older access
restriction syntax. Load the module while we transition Apache
configurations to mod_authz_host.

Implements: blueprint modern-apache
Merge pull request #9 from CiscoSystems/bp/modern-apache

Add mod_access_compat for Apache 2.2 style configs