Add ability to change plugin ID

[Yeregorix]

ModLauncher has removed the - character from valid mod IDs because the Java Module System does not allow this character in module IDs. The consequence is that plugins currently using - will have to change their IDs to continue working on future versions of both SpongeForge and SpongeVanilla.

Currently, uploading a new JAR on Ore with a different plugin ID results in the following error message :

The uploaded plugin ID must match your projects plugin ID.

We need either the ability to change the project's plugin ID, or the ability to upload a JAR with an ID that doesn't match.

[Katrix]

We need to change how we store files before we can this. After that we can probably easily to this