Remove apache::mod::mem_cache from apache::mod::default
Remove apache::mod::mem_cache from apache::mod::default

As per
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Migration_Planning_Guide/ch04s04.html
mem_cache is also no longer supported by redhat.

dzmitryv/puppetlabs-apache,samuelb/puppetlabs-apache,digitalmediacenter/puppetlabs-apache,buzzdeee/puppetlabs-apache,digitalmediacenter/puppetlabs-apache,samuelb/puppetlabs-apache,gerhardsam/puppetlabs-apache,FlatKey/puppetlabs-apache,traylenator/puppetlabs-apache,svanhart/puppetlabs-apache,buzzdeee/puppetlabs-apache,eputnam/puppetlabs-apache,yakatz/puppetlabs-apache,FlatKey/puppetlabs-apache,traylenator/puppetlabs-apache,guegue/puppetlabs-apache,guegue/puppetlabs-apache,eputnam/puppetlabs-apache,svanhart/puppetlabs-apache,gerhardsam/puppetlabs-apache,yakatz/puppetlabs-apache,puppetlabs/puppetlabs-apache,puppetlabs/puppetlabs-apache,bmjen/puppetlabs-apache,dzmitryv/puppetlabs-apache,bmjen/puppetlabs-apache