Add methods, update phpdoc, update readme

* Add new methods (assertTrue, assertNotEquals, assertNotSame)
* Rename assertEqual in assertEquals and assertIdentical in assertSame
(add alias for deprecated methods)
* Update phpdoc
* Append documentation in readme
* Rewrite exemples with new methods
Add unitary test

Add unitary test to test Testify with Testify !
Merge pull request #16 from BafS/master

New methods, clean the code, update readme, add unitary test