#16: Added wildcard and property placeholder supoprt in the SpringApplic...

...ation String defined sources

* Default resource loaded in the BeanDefinitionLoader has been changed to PathMatchingResourcePatternResolver;
* A check for the ResourcePatternLoader similar to that in AbstractBeanDefinitionReader and property placeholder resolution has been added to the load(CharSequence) method of the BeanDefinitionLoader;
* Added a unit test illustrating the issue;