Fix deletion of array items

[RubyRubenstahl]

Problem

The delete operator is used to remove properties from objects and items from arrays. When delete is used on an array, the item is removed, but the array is not re-indexed;

let a=[1,2,3,4];
delete a[1];

// a now equals [1,,3,4]

If deleteByDot is used on an array that subsequently stored through a feathers service, the resulting array in the database (using the mongoose driver, at least) results in the "deleted" item being replaced with null rather than being completely removed.

Proposed Solution

The pull request tests to see if the item to delete is an array. If it is, splice is to remove the array item. Otherwise, delete is used.

Potential Problems

Because this results in different output, it could potentially break code that relies on the current behavior.

[eddyystop]

Thanks for this PR.

I'm leary of starting to add special cases to the byDot utilities, because this could become neverending. You did the work and added a test, so how can I say no?

[eddyystop]

Published to npm as v4.11.0