Add StatementListProvider interface
Update release notes
Merge pull request #5 from Benestar/statementlistprovider

Add StatementListProvider interface
Create ConstraintFactory
Create ConstraintFactoryTest
Update release notes
Fix rebase
Fix method comments in ConstraintFactory
Merge pull request #2 from Benestar/constraintfactory

Create ConstraintFactory
Create DiffRangeConstraint
Update release notes
Create DiffRangeConstraintTest
Fix test
Add DiffRangeConstraint to ConstraintFactory