Add Field, DataModel, DataModelObject, and some more test data.
Added constraint class.
Started adding calculations.
Finished implementing calculation subclasses.
DataModel metadata and fetching objects done.

Partial implementation of acceleration methods on DataModel.
Finished implementing field. More progress on DataModelObject.
Finished implementing DataModelObject, Constraint, and Calculation.
Implemented subtypes of DataModelObject.
First messings around for pivot.
More pivot work. Updated all unit tests to JUnit 4 style.
Implemented pivot filters.
Implemented row splits for pivots.
Implemented pivot column splits.
Finished cell values, and started implementing pivot method.
Merge branch 'develop' into fross/datamodel
Implemented pivot methods and Pivot class.

Cleaned up some imports in ResultsReaderXml (unrelated).
Started on JavaDoc pass.
Finished JavaDoc pass.
Fixed broken build that Fred left.
Wrote end to end example and resolved a few bugs that cropped up while doing so.