Improve naming of validation concepts

--HG--
rename : domain/src/main/java/org/testinfected/petstore/validation/Validation.java => domain/src/main/java/org/testinfected/petstore/validation/Report.java
rename : domain/src/main/java/org/testinfected/petstore/validation/Validate.java => domain/src/main/java/org/testinfected/petstore/validation/Validates.java