DATACMNS-506 - PreferredConstructorDiscoverer now uses Spring 4's ParameterNameDiscoverer if present.

We now also reflectively check for the presence of DefaultParameterNameDiscoverer. This allows the usage of the new reflection methods introduced in Java 8 if the user code is running on Spring 4.

Changed the name of the constant for the ParameterNameDiscoverer in Parameters to meet conventions for constants.
DATACMNS-506 - Added section on escaping underscores in query method names.

We now explicitly discuss the case of referring to properties with underscores (e.g. first_name) in repository query methods.

Added missing language declaration for a code block.