Load SecurityConfiguration only once

Previously the SecurityConfiguration was loaded in the
ContextLoaderListener's ApplicationContext and in the DispatcherServlet's
ApplicationContext. This meant that there were duplicate objects for the
SecurityConfiguration being created. One specific problem that could occur
is that the InMemoryTokenStore would be created twice and if different
instances were used for storing and retrieving the AccessToken's it would
be impossible to authenticate with OAuth.

Now SecurityConfiguration is only loaded once. To accomodate this, the
SecurityConfiguration is loaded by the DispatcherServlet and we instruct
the DelegatingFilterProxy to load from the Dispatcher's ApplicationContext.
It is necessary to have the Spring Security OAuth configuration created in
the child context in order for Spring MVC to find the additional mappings.
Use java.awt.Desktop to open the URL

Previously the solution to open the web browser used Mac specific setup.

Now java.awt.Desktop is used for opening the web browser which provides
support for other OS's and other web browsers.
Remove invalid hibernate.hbm2dll.auto value

The value create-update is invalid for hibernate.hbm2dll.auto. Valid values
are validate, create, update, and create-drop. Furthermore, setting
HibernateJpaVendorAdapter's generateDdl will set the hibernate.hbm2dll.auto
value correctly, but this explicit setting is removing the valid
configuration.
Use Spring Security Java Configuration
Merge pull request #6 from rwinch/javaconfig

Javaconfig and Polish