DATACMNS-533 - Discover declared functions on EvaluationContextExtension.

We new automatically register public static methods declared on classes extending EvaluationContextExtensionSupport as functions to be used within SpEL expressions.

Related pull request: spring-data-jpa#101
Related ticket: DATAJPA-564
DATACMNS-533 - Discover declared properties on EvaluationContextExtension.

We new automatically register public static fields declared on classes extending EvaluationContextExtensionSupport as properties to be used within SpEL expressions.

Related pull request: spring-data-jpa#101
Related ticket: DATAJPA-564
DATACMNS-533 - Support scoping for functions provided by  EvaluationContextExtension.

Added test case for scoped functions.

Related pull request: spring-data-jpa#101
Related ticket: DATAJPA-564