Allow disabling check for file, next to skipping complete file

[Anton-4]

For elm-visualization we would like to disable some rules for certain files, not skip the entire file from analysis.

I propose this to be configured as follows:

{
    ...
    "disabledChecksForPaths" : [
        { "paths":
            ["src/Folder1", "src/Folder2/File1.elm"],
          "checks":
            ["NoTopLevelSignature", "UnusedTopLevel"]
        }
    ],
    ...
}

Once the configuration is agreed upon I am willing to implement this myself.