Fix deprecation warnings

Recent systemd include a warning message when StandardOutput /
StandardError is set to "syslog" in a unit file [15812].

Quoting [poettering] from another PR which caused him to create this
one:
> StandardOutput=syslog is long obsolete, we don't document it anymore
> even. it enables forwarding to syslog even when journald wouldn't do
> that normally.
>
> Simply don#t use StandardOutput=syslog. The implied service default is
> StandardOutput=journal anyway, which does not suffer by this problem.

So simply remove these lines and honor the DefaultStandardOutput /
DefaultStandardError if the admin set them.

[15812]: systemd/systemd#15812
[poettering]: systemd/systemd#15807 (comment)

packager/templates/debian/generic/broker.service

@@ -3,8 +3,6 @@ Description=The Choria Orchestrator Network Broker
 After=network.target
 
 [Service]
-StandardOutput=syslog
-StandardError=syslog
 LimitNOFILE=51200
 User=root
 Group=root

packager/templates/debian/generic/server.service

@@ -3,8 +3,6 @@ Description=The Choria Orchestrator Server
 After=network.target
 
 [Service]
-StandardOutput=syslog
-StandardError=syslog
 User=root
 Group=root
 ExecStart={{cpkg_bindir}}/{{cpkg_name}} server --config={{cpkg_etcdir}}/server.conf