Run the TravisCI build also on PHP 5.5
Zend_Validate_Db_* tests pass proper arguments to constructors.

It is possible to pass either $options array or more parameters. Not both.
Merge pull request #137 from mhujer/tests-zend-validate-db

Fixed Zend_Validate_Db_* tests
Merge pull request #136 from mhujer/travis-php-5-5

Run the TravisCI build also on PHP 5.5