Puppet 2.6.x compatibility fix

Removes a comma that puppet versions 2.6.x complain about, no such problems with 3.x, but as "most" distributions still use 2.6 versions might as well fix it.

Fixes:
<pre>
Error 400 on SERVER: Syntax error at ')' at /etc/puppet/modules/concat/manifests/init.pp:71
</pre>