Make saveUnknown work recursively

[dobrynin]

Summary:

When fetching from DynamoDB with saveUnkown === true, nested fields do not get returned. This PR aims to fix that.

GitHub linked issue:

Closes #323

Type (select 1):

• Bug fix
• Feature implementation
• Documentation improvement
• Testing improvement

• Test added to report bug (GitHub issue #--- @---)
• Something not listed here

Is this a breaking change? (select 1):

• 🚨 YES 🚨
• No
• I'm not sure

Is this ready to be merged into Dynamoose? (select 1):

• Yes
• No

Are all the tests currently passing on this PR? (select 1):

• Yes
• No

Other:

• I have searched through the GitHub pull requests to ensure this PR has not already been submitted
• I have updated the Dynamoose documentation (if required) given the changes I made
• I have added/updated the Dynamoose test cases (if required) given the changes I made
• I have run npm test from the root of the project directory to ensure all tests continue to pass
• I agree that all changes made in this pull request may be distributed and are made available in accordance with the Dynamoose license
• All of my commits and commit messages are detailed, explain what changes were made, and are easy to follow and understand
• I have confirmed that all my code changes are indented properly using 2 spaces
• I have filled out all fields above

[coveralls]

Pull Request Test Coverage Report for Build 818

• 10 of 12 (83.33%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.003%) to 85.504%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/Attribute.js	9	11	81.82%

Totals
Change from base Build 810:	-0.003%
Covered Lines:	2188
Relevant Lines:	2482

---

💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 823

• 12 of 12 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.03%) to 85.479%

---

Totals
Change from base Build 810:	-0.03%
Covered Lines:	2188
Relevant Lines:	2482

---

💛 - Coveralls

[dobrynin]

I would also like to add an option to errorIfFetchingUnknownAttribute or something to that effect. Any thoughts on this?

[fishcharlie]

Looks good at first glance. We for sure need tests for this. I'd also like to see some more comments explaining a bit more what exactly this is doing, just to make it easier for future devs to work on it.

[fishcharlie]

@dobrynin #522 (comment)

I would also like to add an option to errorIfFetchingUnknownAttribute or something to that effect. Any thoughts on this?

I'm all for that, so long as the default stays as the current behavior (no breaking change). It also probably makes sense to have that be a separate PR.

[dobrynin]

@fishcharlie, I've added your requested changes. As for making a new PR for errorIfFetchingUnknownAttribute, what's the best way to do that? Wait for this to be merged? Branch off of this branch?

[fishcharlie]

LGTM