Add database options to ParseServer constructor and pass to MongoStorageAdapter

[steven-supersolid]

This should allow being able to pass options when connecting to MongoDB, such as setting the connection pool size.

[codecov-io]

Current coverage is 90.67%

Merging #956 into master will decrease coverage by -0.68% as of 01286ef

@@            master    #956   diff @@
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  Files           73      73       
  Stmts         4324    4398    +74
  Branches       863     880    +17
  Methods          0       0       
======================================
+ Hit           3950    3988    +38
  Partial         10      10       
- Missed         364     400    +36

Review entire Coverage Diff as of 01286ef

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[flovilmart]

@steven-supersolid could you add a few tests there to make sure the adapter is loaded with the proper options etc...

[facebook-github-bot]

@steven-supersolid updated the pull request.

[flovilmart]

LGTM