update Guardfile to match refactoring of quby engine and tests
added check for score length not longer that 13 chars
allow up to 19 characters to be in question keys
validate scores: uniqueness and length
raise if non-unique keys exist
split tests
rename spec and remove pointless expectations
removed non-unique score key validation

This validation is pointless as repeated keys are being overwritten by design
in https://github.com/roqua/quby_engine/blob/master/spec/quby/questionnaires/entities/questionnaire_spec.rb#L72
let questionnaire raise on double score keys
Merge pull request #87 from roqua/im-check-score-key-length

added check for score length not longer that 19 chars