Files cleanup

[Pezhvak]

First of all thanks for making this awesome repository.

As I was testing notea, i noticed uploaded images don't get deleted if they are removed from the note, I even tried deleting the note (from trash too) and the files still remain.

I'm not sure if it's handled behind the scenes or not, but if system loose track of these files it will create trouble in the long run.

Is there anything that I'm missing?