Configure Guard to run all specs when a shared spec changes
Remove needless visibility change from Representations::Abstract#initialize
Refactor SingleByteXorCracker method parameter names to reflect contract
Refactor to simplify by using Enumerable#sort_by instead of #sort
Solve Set 1, Challenge 6

* Factor out Abstract#normalcy_score
* Refactor Refinements::StringRefinements into Refinements::Array
* Factor out FrequencyAnalyzer from SingleByteXorCracker
* Factor out Util from Set01::Challenge05 and SingleByteXorCracker