Adds ..builds_callable_method_name.. (not_empty -> validateNotEmpty)
Extracts nested controls in validate. Adds getCallableRuleFromName().

- Changes convention from validate_not_empty to validateNotEmpty etc..
- getCallableRuleFromName left as public for testing purposes ... bad?
Renames methods. Extracts setFieldValidationFailed($field_name, $callable_method)
Refactors tests. Adds validation tests.

- Rearranges methods
- it_builds_callable_method_from_validate_rule_name
- it_validates_an_email_address
- it_validates_not_empty
src - validateEmail returns bool. Adds translateRuleNameToMethodName
Minor refactor....
Updates validation usages
Validation - tests/implements it_can_also_accept_a_closure_in_place...