Rename Common to Shared in the default rojo project

[nezuo]

This is what rojo init generates by default:

"ReplicatedStorage": {
  "Common": {
    "$path": "src/shared"
  }
},

The name of the folder should match the name of the shared directory.

If this gets the go-ahead I can make a PR.

[LPGhatguy]

This makes sense to me, these names should match.

That said, do you think there is a better naming scheme we can use for this folder?

[nezuo]

Nothing comes to mind but all the projects I've seen have used Shared.