(FACT-237) Add directed graph for handling dependencies
(FACT-237) Add aggregate resolution class
(FACT-237) Implement deep_merge for composing facts
(FACT-237) Implement deep_freeze for composed facts
(FACT-237) Use specific error classes for deep_merge and deep_freeze
(FACT-237) Freeze results of each aggregate chunk
(FACT-65) Don't rescue aggregate errors

Before this commit, errors occurred while evaluating an aggregate
resolution would be rescued and logged, which could mask problems and
cause more failures later. This commit removes the error handling so
that evaluations fail early.
(FACT-237) Define default aggregate action