v6.2.0: Add hover interaction on File Item and other fixes

🧪 New features

• Webpage in beta version was released. You can visit dropzone-ui.com. In there you can find a nice code generator.
• <FileItem/>: Added alwaysActive prop. This prop provides hover interaction. If false (by default), FileItem will hide the main layer with all the buttons except the file validation status and the upload status. If true, main layer will be visible all the time.
• <FileItem/>: Added elevation prop. This prop provides the user to decide about the shadow and border on the FileItem container.

🐛 Fixes or improvements

• <Dropzone/>: Fixed Spanish translation on footer.
• <Dropzone/>: Hide "view" button when view prop is provided.
• <Dropzone/>: Fix issue that hides dropzone label when FileItems are outside.
• <Dropzone/>: Fixed minor issues on minHeight.
• <FileItem/>: Hide "delete" button when onDelete prop is not provided
• <FileItem/>: Change word-break css propertie from break-all to break-word;

📚 Improved documentation.