Fixed defect http://code.google.com/p/owasp-esapi-php/issues/detail?id=10
Fixed defect http://code.google.com/p/owasp-esapi-php/issues/detail?id=10

Changes
* At least two tests per exception class
* Default constructor now tested with asserts to make sure default Exceptions are constructed properly.
gpedro/PHP-ESAPI,jollysean/PHP-ESAPI,OWASP/PHP-ESAPI,najamelan/PHP-ESAPI,jollysean/PHP-ESAPI,gpedro/PHP-ESAPI,gpedro/PHP-ESAPI,najamelan/PHP-ESAPI,OWASP/PHP-ESAPI,najamelan/PHP-ESAPI,jollysean/PHP-ESAPI,OWASP/PHP-ESAPI