Doesn't support an array of main files

[dotnetCarpenter]

When used with polymer I get:

path.js:7
    throw new TypeError('Path must be a string. Received ' + inspect(path));
    ^

TypeError: Path must be a string. Received [ 'polymer.html', 'polymer-mini.html', 'polymer-micro.html' ]
    at assertPath (path.js:7:11)
    at Object.join (path.js:466:7)
    at extractMain (C:\Users\dotnet\Projects\firefund\styleguide\node_modules\bower-copy\index.js:50:21)

bower-copy clearly doesn't support main as array