Signing modules without having them distributed by FreePBX

This is a suggestion to open up signing of modules to GPL2 components which are not actually distributed by FreePBX but are included in other distributions such as PBX in a Flash and Incredible PBX. The advantage is that these users could still use FreePBX 12's module signing capability and the extra layer of security it affords while using additional GPL2 modules (mostly iframe wrappers to existing GPL2 products such as AsteriDex, AvantFax, and others) that are included in PBX in a Flash and Incredible PBX as a convenience. These wrappers allow management of all resources from within the FreePBX GUI.