clean all upstart process files

instead of cleaning only for the number of processes defined in the
formation, we now remove all files using a glob.

intentionally not moving the glob higher up, because that has a higher
risk of matching files that do not belong to the application.

fixes ddollar#646

lib/foreman/export/upstart.rb

@@ -13,15 +13,18 @@ def export
 
     engine.each_process do |name, process|
       process_master_file = "#{app}-#{name}.conf"
-      clean File.join(location, process_master_file)
+
+      Dir[
+        File.join(location, process_master_file),
+        File.join(location, "#{app}-#{name}-*.conf")
+      ].each { |f| clean(f) }
 
       next if engine.formation[name] < 1
       write_template process_master_template, process_master_file, binding
 
       1.upto(engine.formation[name]) do |num|
         port = engine.port_for(process, num)
         process_file = "#{app}-#{name}-#{num}.conf"
-        clean File.join(location, process_file)
         write_template process_template, process_file, binding
       end
     end