Update zipCode.js

zipCode validator should default to a non-empty test instead of testing all unsupported countries against the US zipcode format.
initial german translation
Create it_IT.js
#426: Add test suite for the zipCode validator
#452: Update zipCode document typo, thanks to @mike1e
#456: Adjust the feedback icon position for .input-group element
Fix the link to iCheck

Under compatibility there is 'iCheck' project.
The domain http://fronteed.com/ is no longer reachable.
The link was updated to go straight to the GitHub project, where the README.md is viewable.
Merge pull request #461 from nathanrosspowell/master

Fix the link to iCheck in README.md
Add @phillprice and @nathanrosspowell to the list of contributors
#465: Support dynamic message
#430: greaterThan adds support for comparing to other field, return value of a callback function
#430: lessThan adds support for comparing to other field, return value of a callback function
#430: between adds support for comparing to other field, return value of a callback function
#465: Refactoring zipCode validator
#465: Refactoring between validator
#465: Refactoring greaterThan, lessThan validator
#465: Refactoring choice validator
#465: Refactoring step, stringCase, uuid validators
#465: Refactoring id validator
#465: Refactoring iban validator