The role of the master server as the party controlling every part of the
cluster is not well reflected in its name and has caused confusion among
users on several occasions. Rename master to controller to better
reflects its role.
Enforce the filename of uploaded mods match {name}_{version}.zip with
name and version taken from the zip file's info.json entry. This allows
it to be used as a unique key for the mod and solves part of the issues
with mods having different number of leading zeros in their version.
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 the ability to manage a set of mods to be shared by the master
server to the rest of the cluster. This implements storage, uploads,
downloads, deletetion, and listing details of mods but does not actually
do anything with the stored mods.