Fixed Exception class in "Informative Exceptions"

The example in the "Informative Exceptions" section uses InvalidArgumentException, which is incorrect as that class does not have a getFullMessage() method. The class that defines getFullMessage() is AbstractNestedException, of which DomainException is a subclass, so I've replaced InvalidArgumentException with that to make the example accurate.
7 digits phone numbers should be valid.
Translate date formats to something DateTime::createFromFormat can understand.
Add minimum php required version to composer.json
Merge pull request #212 from malukenho/patch-4

Add minimum php required version to composer.json
Merge pull request #211 from osiux/issue-152

Translate Date formats to DateTime::createFromFormat
Merge pull request #210 from osiux/issue-187

7 digits phone numbers should be valid.
Merge pull request #201 from elazar/patch-1

Fixed Exception class in "Informative Exceptions"
Create RuleName rule