Make all properties on the mod pack object except sha1 required and add
the base mod if it does not exist in order to align the JSON
representation with the proposed Mod Pack String format I published on
the Factorio Forums (https://forums.factorio.com/103578)
The Factorio Mod Portal uses and provides SHA1 hashes of mods, so it
makes sense to align the ModPack and ModInfo structures to sha1 by
renaming the genericly named hash property to sha1.
Add ModPack data type with corresponding storage on the master, messages
to create, update and delete them, as well as commands to invoke them.
The ModPack data type contains a list of mods with versions and optional
sha1 hashes, and mod settings to be used.
Hornwitser