Clean the webclient unpack dir safely.

Don't rely on a puppet file resource to purge the unpack dir as this
will trigger on every puppet run then copy the empty unpack dir to the
deployment dir. Instead we call rm prior to tar during the unpack exec
so that we only ever clean the dir if we are unpacking.

Change-Id: I80b4faf54220d88e610e2a224dea47af4133e225

manifests/application.pp

@@ -217,19 +217,17 @@ class storyboard::application (
     onlyif  => "curl -I ${webclient_url} -z ./${webclient_filename} | grep '200 OK'",
   }
 
-  # Create/clean the storyboard-webclient unpack directory
+  # Create the storyboard-webclient unpack directory
   file { "${src_root_webclient}/dist":
     ensure  => directory,
-    recurse => true,
-    purge   => true,
-    force   => true,
     require => File[$src_root_webclient],
   }
 
-  # Unpack storyboard-webclient
+  # Clean the unpack dir then unpack storyboard-webclient
   exec { 'unpack-webclient':
-    command     => "tar -xzf ../${webclient_filename}",
+    command     => "rm -rf * && tar -xzf ../${webclient_filename}",
     path        => '/bin:/usr/bin',
+    provider    => shell,
     refreshonly => true,
     cwd         => "${src_root_webclient}/dist",
     require     => [