Make sure the className is correct for results on unknown relations

[andrewimm]

If the target className of a relation is not known ahead of time, and the server does not pass the className back on the raw JSON of Parse Object results, the query results end up with the wrong className.
The className to be used comes back as a top-level key on the query result payload. This diff makes sure that value is used, if available.

[codecov-io]

Current coverage is 79.55%

Merging #179 into master will increase coverage by +0.08% as of 94eed4c

@@            master    #179   diff @@
======================================
  Files           39      39       
  Stmts         2997    2998     +1
  Branches       713     714     +1
  Methods          0       0       
======================================
+ Hit           2382    2385     +3
+ Partial        200     197     -3
- Missed         415     416     +1

Review entire Coverage Diff as of 94eed4c

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[peterdotjs]

lgtm.