splunk-connect-for-kubernetes: Logging does not successfully use hec_ca_file for cert verification by default

When running splunk-kubernetes-logging 1.1.0 on OpenShift 3.11, I encountered the following error:

[warn]: #0 failed to flush the buffer. retry_time=0 next_retry_seconds=2019-04-11 23:31:24 +0000 chunk="234234234234" error_class=OpenSSL:SSL::SSLError error="SSL_connect returned=1 errorno=0 state=error: certificate verify failed (unable to get local issuer certificate)"

In order to work-around the problem, I added the following environment variable definition to the Logging fluentd-hec container in the Logging Daemonset:

env:
- name: SSL_CERT_FILE
  value: /fluentd/etc/splunk/hec_ca_file