Update mongoose npm package to v5.5.5

[dhuang612]

I reviewed the test errors that were happening

     TypeError: Cannot read property '$handleCallbackError' of undefined

with this being the error.

I found that some of the tests had extra .chains that were including stuff such as

.chain('limit')

But they weren't being called with params
as talked about on this SO question
https://stackoverflow.com/questions/44188675/unit-testing-mongoose-model-callback-with-sinon

I removed those extra params and got a new error.
Through research I figured out how to return the results of the tests to be errors and updated the code.
I then ran npm test and confirmed the errors were gone.

Please let me know if anything else needs to be resolved.

Thanks

[dhuang612]

I can bump the mongoose package up to v 5.8 so that the bot stops trying to merge new commits
@YasharF