Add option to replace files without creating backups

[niyazpk]

Right now if my grunt looks like this:

imagemin: {
  dist: {
    files: {
      'html/img/compressed/cart.png': 'html/img/cart.png',
    }
  }
}

.. and if I run the task multiple times, a file with name cart.png.bak is created in the compressed directory. Please consider adding an option to turn this off.

(Or is this an option that can be passed to OptiPNG? In that case the documentation should mention that).

[hugomrdias]

this would be nice
i have to setup another task to delete those :D

[jeffwhelpley]

I agree with this. When you have an build script that you have tested and know it works, you don't need to create extra backups.