Custom logging for apache::vhost

This patch adds the ability to change how vhost logging works. This patch
adds new parameters to 'apache::vhost' define type. This allows users to
specify a log format or nickname for the 'CustomLog' directive. This also
allows users to specify a pipe as the destination for the 'ErrorLog' and
'CustomLog' directives.
Spec tests for apache::vhost logging improvements

The enhancements to vhost logging are currently passing the previous
spec tests in place. However the enhancements added two new ways the
apache::vhost type should fail. The enhancements also added some extra
logic surrounding the CustomLog and ErrorLog directives.

This patch extends the suite of tests already running against
apache::vhost logging enhancements added in 4226690eb3. The new
tests verify the correct functionality of the logging enhancements.
Add documentation for apache::vhost logging

Commit 6f4a317 added new paramters for controlling logging for the
apache::vhost type. This commit adds documentation for those changes.
Refactor apache::vhost log file destination logic

This commit combines the blocks of logic determining the apache::vhost
logging values.
Merge pull request #184 from trlinkin/refactor_vhost_logformat

Refactor vhost logformat