* Refactored Document and TimingMetadata to not extend Attribute

[ivakegg]

• Simplified any logic looking for nested documents

[apmoriarty]

LGTM. Nice cleanup.

[jwomeara]

I kind of rushed through this at the end once i got to the tests, but I had a few comments.

[billoley]

In DocumentProjection, the following constructor arguments and class memebers are no longer used. Is this intentional?
If so, they should probably be removed from the constructor and the class.

private final boolean includeGroupingContext;
private final boolean reducedResponse;    
private boolean trackSizes = true;

public DocumentProjection(boolean includeGroupingContext, boolean reducedResponse, boolean trackSizes, Set<String> projections, Projection.ProjectionType projectionType) {
    this.includeGroupingContext = includeGroupingContext;         // no longer used
    this.reducedResponse = reducedResponse;                            // no longer used
    this.projection = new Projection(projections, projectionType);
    this.trackSizes = trackSizes;                                                      // no longer used
}

[ivakegg]

@billoley Cleaned up those members and constructors. Thanks!