Introduce ExtDirectSpring

Introduced the Java/Spring implementation of the Ext-Direct technology. The following sites provide detailed information:

- http://www.sencha.com/products/extjs/extdirect
- https://github.com/ralscha/extdirectspring/wiki
- https://github.com/ralscha/extclassgenerator
- https://github.com/ralscha/extclassgenerator-annotations

The webapp-archetype has also been adapted. (Missing person- and user-daos and -services have been added, too.)

Please review and merge!