[COOK-3900] Apache HTTP 2.4 Support

This provides Apache 2.4 support in a backwards compatible way. 
It adds the following new attributes:
- `apache.version` - This defaults to `2.2` and if changed to `2.4`; it triggers and assumes 2.4 packages will be installed.
- `apache.mpm` -  In 2.4 mode, this specifies which mpm to install. Default is `prefork`.
- `apache.run_dir`
- `apache.lock_dir`
- `apache.prefork.maxrequestworkers`
- `apache.prefork.maxconnectionsperchild`
- `apache.worker.threadlimit`
- `apache.worker.maxrequestworkers`
- `apache.worker.maxconnectionsperchild`
- `apache.event.startservers`
- `apache.event.serverlimit`
- `apache.event.maxclients`
- `apache.event.minsparethreads`
- `apache.event.maxsparethreads`
- `apache.event.threadlimit`
- `apache.event.threadsperchild`
- `apache.event.maxrequestsperchild`
- `apache.event.maxrequestworkers`
- `apache.event.maxconnectionsperchild` 
- `apache.itk.startservers`
- `apache.itk.minspareservers`
- `apache.itk.maxspareservers`
- `apache.itk.maxrequestworkers`
- `apache.itk.maxconnectionsperchild`

Notes:
- `mod_auth_openid` - TODO: build package dependencies need to updated for 2.4 support.
- `mod_proxy` -   In 2.4 mode, `apache.proxy.order`, `apache.proxy.deny_from`, `apache.proxy.allow_from` are ignored, as the attributes can not be supported in a backwards compatible way. We will want to setup a different way to approach it.

Apache Modules I did not test for 2.4 support, but should work with the right package:
- `mod_auth_cas` - ubuntu: depends on `apache2.2-common (>= 2.2.3-2)`.
- `mod_charset_lite` - ubuntu: depends on `apache2.2-common`.
- `mod_fastcgi` - ubuntu:  depends on `apache2.2-common (>= 2.2.4)`
- `mod_fcgid` - ubuntu: depends on `apache2.2-common`.
- `mod_perl` - ubuntu: depends on `apache2.2-common`.
- `mod_python` - ubuntu: depends on `apache2.2-common`.
- `mod_wsgi` - ubuntu: depends on `apache2.2-common`.
- `mod_xendfile` - ubuntu: depends on `apache2.2-common (>= 2.2.3)`
- `mod_dav_svn` - ubuntu: depends on `libapache2-svn`.
- `mod_lua` - ubuntu: experimental module failed because of missing shared object file
- `mod_pagespeed` - no `mod_pagespeed` package available

https://tickets.opscode.com/browse/COOK-3900
http://httpd.apache.org/docs/current/upgrading.html