At support for logger

One logger to be used by the repository of rules are added.
Cahgne Ruler library

Forked version of ludycruz adds arithmetic operator, we nned this.
Until this is added to mainstream this repo will be used.
Improve Repository interface and tests

Cahnged the RuleRepository to take into account technical issues
when evaluating rules. Added more tests and another Repository, this
one generated by the dsl tool. Add logger for testng purposes when
firing the rules action.
Add arithmetic rule to tests

Now we can fully declare complex expressions.
Add another generated rule

Add tests for the new generated rule using arithmetic expressions.
Add improved test and fix some bugs
Merge branch 'master' of https://github.com/michelrc/sheet-validator

Conflicts:
	tests/Payroll/Test/PayrollValidatorTest.php
	tests/Payroll/Test/Rules/TruthTable.php
	tests/Payroll/Test/Rules/TruthTableGenerated.php
	tests/Payroll/repository/truth-table.ods
Merge pull request #3 from michelrc/master

Updates with validators and rules