Improve Praspel asserter

Here is an example test : https://github.com/jubianchi/PHPSandbox/blob/master/praspel-atoum/test.php

Minor changes to the syntax.
Here is the output when I run the test

```
vendor/bin/atoum -f test.php                                                      
> PHP path: /usr/bin/php5
> PHP version:
=> PHP 5.4.9-4ubuntu2 (cli) (built: Mar 11 2013 16:09:26)
=> Copyright (c) 1997-2012 The PHP Group
=> Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies
> tests\units\SUT...
[FFF_________________________________________________________][3/3]
=> Test duration: 0.00 second.
=> Memory usage: 0.00 Mb.
> Total test duration: 0.00 second.
> Total test memory usage: 0.00 Mb.
> Running duration: 0.09 second.
Failure (1 test, 3/3 methods, 0 void method, 0 skipped method, 0 uncompleted method, 3 failures, 0 error, 0 exception) !
> There are 3 failures:
=> tests\units\SUT::test M1 n°1():
In file /home/jubianchi/repositories/jubianchi/PHPSandbox/praspel-atoum/test.php on line 32, Hoathis\Atoum\Test\Asserter\Praspel::verdict() failed: Verdict was false
=> tests\units\SUT::testM2n°1():
In file /home/jubianchi/repositories/jubianchi/PHPSandbox/praspel-atoum/test.php on line 42, Hoathis\Atoum\Test\Asserter\Praspel::verdict() failed: Verdict was false
=> tests\units\SUT::testFoobarn°1():
In file /home/jubianchi/repositories/jubianchi/PHPSandbox/praspel-atoum/test.php on line 52, Hoathis\Atoum\Test\Asserter\Praspel::verdict() failed: Verdict was false
```