Pulled out RuleFactory with a default rule

First step towards polymorphism replacing conditional logic
Made rules stateless, moved existing tests to acceptances tests

Introduced isolated unit tests for Inventory
Pulled out Rule for Sulfuras

1) Created the Frozen rule + tests
2) Used EclEmma to see which parts of DoEverythingRule was no longer
being exercised
3) Removed dead code, we are on our way!