Remove product update upload

The old style product update uploads are no longer used.  The only update from the old days is the smart proxy and that does not get populated in the maintenance tab through "upload," it will be populated into the database from the filesystem if it exists.

I need help on removing the code in the UI as it will change the display on the maintenance tab's view template:

```
git grep upload_updates
vmdb/app/views/ops/_settings_maintenance_tab.html.erb:    <%= form_tag({:action    => "upload_updates"},
```

@h-kataria @dclarizio @martinpovolny Anyone want access to my fork to push the remaining deletions?

cc @brandondunne  :see_no_evil: 
Good call @brandondunne, I don't see it referenced so I dig into git and you missed an opportunity to delete that line when the only use of that line "product_update_activation_initiated" was removed...  I'll take it from here...

```
commit d501fd036854e7fe913c40e1405277b7cc783aad
Author: Brandon Dunne
Date:   Fri Sep 6 22:45:14 2013 -0400

    Remove ProductUpdate.server_activate_update and disable caller
```