SEC-2114: Spring Cache abstraction based UserCache implementation

[spring-projects-issues]

Marten Deinum (Migrated from SEC-2114) said:

Spring has a cache abstraction since 3.1 would be nice if Spring Security took advantage of this where appropriate.

[spring-projects-issues]

Marten Deinum said:

Created a pull request.

#23

[spring-projects-issues]

Marten Deinum said:

The proposed changes should be fine.