Fix dependency loop in vhost

Also fix missing backslash from test for rewrites.
Merge pull request #820 from mhaskel/vhost_fixes

Fix dependency loop in vhost
Allow other manifests to define ::apache::mod{ 'ssl': }.

This will allow Apache from the httpd24 SCL on RHELish systems to
include the proper mod_ssl package while still letting ssl
::apache::vhost defines work as expected.

Add package_name param to ::apache::mod::ssl.

Add a test for the package_name parameter.

Update the package_name parameter test.