electron-dir-files

In Electron, use the webkitdirectory property in input element has bug.

So I used Electron Dialog get the directory name, and create the fakeBrowserFile for renderer-process,
You can use it for existing Browser JavaScript Library, but modified a little.

``javascript
let electronDirFile = require('electron-dir-files');

someElement.addEventListener('click', () => {
electronDirFile().then(files => {
// use the files like webkitdirectory get
})
})

// fakeBrowserFile to Blob
file.toBlob().then(blob => {
// blob is the file
})

let slicer = file.slice(0, 100);
slicer().then(blob => {
// the slice blob
})

``