Disable noop mode for concat dependencies

Disabling noop mode for the concat dependencies allows one to see diffs
of the concat target when applying with the noop flag:

Example:

  echo BAR > /tmp/foo.txt

  tee puppet.conf <<EOF
  [main]
  pluginsync = true
  EOF

  tee puppet.pp <<EOF
  concat { '/tmp/foo.txt': }

  concat::fragment { 'FOO':
    target => '/tmp/foo.txt',
    content => "FOO\n",
    order => '01',
  }
  EOF

  sudo puppet apply --show_diff --noop \
    --modulepath=/tmp/modules \
    --confdir=/tmp puppet.pp

Output:

  Notice: Compiled catalog for lollipop in environment production in 1.03 seconds
  Notice:
  /Stage[main]/Main/Concat[/tmp/foo.txt]/File[/tmp/foo.txt]/content:
  --- /tmp/foo.txt        2014-05-12 13:20:16.294807259 -0500
  +++ /tmp/puppet-file20140512-1304-1qq5o8c       2014-05-12
  13:20:23.706673840 -0500
  @@ -1 +1 @@
  -BAR
  +FOO

  Notice:
  /Stage[main]/Main/Concat[/tmp/foo.txt]/File[/tmp/foo.txt]/content:
  current_value {md5}f98bf6f12e995a053b7647b10d937912, should be
  {md5}702970b5f7da2b2f
  718d31ac4f046f5e (noop)
  Notice: /Stage[main]/Main/Concat[/tmp/foo.txt]/File[/tmp/foo.txt]/owner:
  current_value jhathaway, should be root (noop)
  Notice: /Stage[main]/Main/Concat[/tmp/foo.txt]/File[/tmp/foo.txt]/group:
  current_value jhathaway, should be root (noop)
  Notice: Concat[/tmp/foo.txt]: Would have triggered 'refresh' from 3
  events
  Notice: Class[Main]: Would have triggered 'refresh' from 1 events
  Notice: Stage[main]: Would have triggered 'refresh' from 1 events
  Notice: Finished catalog run in 0.43 seconds