Deep delete doesn't work as expected

[xibre]

@rocknrolla777 Hello. First of all, thanks for this awesome mixin.

I tried to set the options as described in the readme, but I have some problems when setting the deepDelete: true in the mixin options. This option is simply ignored and it leads to the skipping of the related model deep deletion (when debug mode is enabled, I can see the "Skipping delete for MyModelName" message printed).

I think this problem is caused by this line. I guess it should instead be:

...
if (relationDeepDelete || options.deepDelete) {
  ...

For now to make deep delete work, I had to set deepDelete: true for all the relations exclusively.