Merge pull request #8 from nilportugues/v1.0

Merge pull request #7 from nilportugues/master
#12 Issue: The function isInstanceOf has a correct behaviour?
Merge branch 'master' of github.com:nilportugues/validator
adaptation + merge with chefchef-master
Update README.md
Merge pull request #13 from nilportugues/master

isPositiveOrZero and isNegativeOrZero plus isInstanceOf reworked, same behaviour.