Drag n drop import - feature request 1522

<h4>Drag and drop file upload</h4>
Video Preview of working code: https://www.youtube.com/watch?v=Hsi46nKsbNI&feature=youtu.be

**Features**
- [x] Drag and Drop sql (or other supported extensions) to PMA interface to initiate FILE uploads. (Allowed files will be uploaded)
- [x] View status of file-upload on bottom right corner of the screen (includes progress percentage)
- [x] Option to abort upload while uploading
- [x] Once upload has finished, show status as success (file was uploaded, and import process was successful), failed (file was uploaded, but import failed) & Aborted (file was not uploaded but aborted)

**todo**
- [ ] Add css for `original`
- [ ] Different icons for different status (success, failed and aborted)
- [ ] Way to advertise this feature, like a message in import page or some tour guide