Adding product image functionality

Issue #37 
## Testing Instructions:
- [ ] Login as admin user, click on create product Try to add a single image, You must be able to add the image, Validate that you can only add a singler image,as per suggested format only.
- [ ] Go to product listing page, You must be able to see the image there.
- [ ] Click on a product you must be able to see the producvt image at product details page.