BREAKING CHANGE: Update files param to handle multiple directories

[haxxxton]

'json-minify': {
    build: {
        files: ['../../../foo/**/*.json', '../../../bar/*.json']
    }
},

produces an error
Warning: Cannot use 'in' operator to search for 'src' in ../../../foo/**/*.json Use --force to continue.

it would appear that files is attempting to do something that we dont want. Changing the name to fileList solves this problem.

Currently i can find no documentation for what files is attempting to do, nor can i find a way to backwards compatible-ize as the error is thrown before the task is run.

[mlegenhausen]

Can you provide a working example? The usage of files should be favoured cause most grunt user know to work with it.

[haxxxton]

Working example would be to switch the noun files for fileList

'json-minify': {
    build: {
        fileList: ['../../../foo/**/*.json', '../../../bar/*.json']
    }
},

I am unsure of why files, when receiving an array of paths, is failing. i agree it would be preferable to stick with files, but im finding that before the json-minify.js task code is even run, grunt throws the above Warning

Warning: Cannot use 'in' operator to search for 'src' in ../../../foo/*/.json Use --force to continue.