Ops: Add Multiple custom access logs and Header field for ATS

[weifensh]

Currently TO supports only one custom access log file by configuring the "LogFormat" and "LogObject" parameters for "logs_xml.config". We have a requirement to support multiple custom access log files. As ATS does support this, we are planning to extend "LogFormat"&"LogObject" on TO, and add extra 9 groups (9 should be enough) of parameters like: "LogFormat1"&"LogObject1", "LogFormat2"&"LogObject2" ... "LogFormat9"&"LogObject9". Only when "LogFormatN"&"LogObjectN" are configured, they will appear in "logs_xml.config"; otherwise the file does not change, so the current behavior does not change either.

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/incubator-trafficcontrol-PR/700/
Test PASSed.

[asfgit]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/incubator-trafficcontrol-PR-trafficops-test/659/

[weifensh]

The UT failure above seems to be caused by the following line of existing code in ApacheTrafficServer.pm:
$self->app->log->error("Parameter package.trafficserver missing for profile ".$server->profile->name . ". Assuming version $ats_ver");