Improper abstract bean definitions handling

When SpringConfiguration tries to load the config file, it iterates throug the whole list of bean definitions, including abstract ones, and tries to get them by name (using getBean() method). If a bean happens to be declared abstract="true", such call raises the exception. This leads to inability of abstract bean usage. I've created a simple and stupid patch, I am sure authors will come up with something more gentle, but that's enought for me.

Please incorporate the fix future releases.