DATACMNS-535 - Build now requires Java 7 to run.

Added Maven Enforcer Plugin to make sure the build is run against a JDK 7.

Related ticket: DATACMNS-532.
DATACMNS-532 - Added support for default methods on repository interfaces.

DefaultRepositoryInformation now excludes default methods from the query methods it detects. RepositoryFactorySupport adds a special MethodInterceptor to the proxy which handles the invocation of default methods.

Related tickets: DATACMNS-535.