Add the isUrl validator, more checks and better type definitions.

• Add the isUrl validator.
• Add var dump check.
• Define return type for several methods.

Added the isEmail validator.

1.0.4

Added the following validator: isEmail.

New validators: isTrue, isFalse and isArray

• Added the following validators: isTrue, isFalse and isArray.

Error messages, to array with no empty properties, and minor changes

• Improve the composer script for running the tests.
• Refactor is validating property for a better naming.
• Change the validate to give messages in case of failed validation.
• Add PHP DOC with the format expected for the getValidationRules method.
• Add the possibility to convert the instance to an array with no empty properties.
• Add to README how to execute the tests.

Add isNull and isNotNull validators. Add linter.

• Add the following validators: isNull and isNotNull.
• Improve documentation of the project. Add linter and phpcs to scripts.

First version

Merge pull request #1 from lfbn/improvement/add-changelog-better-readme

Add Changelog. Improve Readme.