removed unused low and high parameters to getValue
implemented Minute validating value parameter
test updates
updated Hour to validate the value it uses
updated Day to validate the value it uses
implmented validation in Month class
fixed bug in Cron Builder
added more to iValue interface
updated Literal value type with new iValue api
implemented greaterThan and lessThan for Range
implmented lessThan and greaterThan for AList
completed iValue refactor
updated all Items and their tests