allow error_log to be set as httpd_service parameter or node attribute

[kylebevans]

Cookbook version

0.3.6

Chef-client version

12.8.1

Platform Details

RHEL 7.2

Scenario:

setting the errorlog in httpd.conf to "syslog:local6"

Steps to Reproduce:

There is no support for setting the errorlog in either the httpd_service resource or in a node attribute

In httpd/libraries/httpd_service_rhel.rb, line 200 sets the error_log statically. Allow the use of a resource parameter or a node attribute if possible.