fix(import): COMPASS-4206: Fix type detection and export formatting.

[imlucas]

• fix(import): COMPASS-4206: Make type detection/casting work right when importing/exporting .json. a093933

Importing correctly picks up ObjectID, Number, and Date:

• feat(export): Pick up nested objects to include in projection f6baf06

doc = {
  _id: 'Arlo', 
  location: {
    place: 'home',
    activity: {
       sleeping: true,
       is: 'on the couch'
    }
};

Before this would populate the projection as:

• _id
• location

Now you can specify full paths for more control over what is actually returned:

• _id
• location.place
• location.activity.is
• location.activity.sleeping

Use case: (See a 1M line csv imported that is 300 fields wide and you only want 2).

• fix(export): Add tests to make sure csv's have correct headers. df70ff9

Headers should be dotnotation for nested object paths.