Created OAuth2ExpressionParser that automatically wraps a Spring Expression

... with a method that provides meaningful errors.

This allows Spring Security OAuth to check for errors and throw Excepions when an error occurs
while ensuring that the exception is only thrown when necessary. For example, if an expression
has an or statment we do not want to throw the Exception if only part of the expression is false.

Fixes gh-41, Fixes gh-118
Disable anonymous auth for resource server
Ensure AccessDeniedException is thrown from expression handler

... otherwise the AccessDeniedHandler doesn't get a chance to send
the proper response and user just sees 500 status

Fixes gh-118
Support for Jackson2 in JdbcClientDetailsService
Fix potential duplicate token problem in JdbcTokenStore

It shouldn't happen in practice, but the JdbcTokenStore, since it
didn't check for the existence of a token with the same value
before doing an insert, might break confusingly later. I think
I would recommend a uniqueness constraint in the database anyway
but now we have a "last one wins" rule.
Add support for authorization code services in @Configuration