changes in DataCollection:
    features:
      implemented removeWhere, removeAll
    refactor:
      all removal methods now use _removeAll to achieve consistent behavior when removing objects
    other:
      author field added to clear method
minor change in test
Merge branch 'master' into feature/removeAll

Conflicts:
	lib/src/data_collection.dart
	test/data_collection_test.dart
Merge pull request #10 from cleandart/feature/removeAll

changes in DataCollection:
    features:
      implemented removeWhere, removeAll
    refactor:
      all removal methods now use _removeAll to achieve consistent behavior when removing objects
    other:
      author field added to clear method