#24 Add support for Java5 annotations

[Lars Kühne]

Annotations are increasingly to express semantics, like in Spring's @Configured, @Transactional, in Tapestry's @Inject and @NonVisual, etc.

If an annotation (or one of it's args) on a method or field changes, this should be reported by clirr.

Not sure what to do with annotations on private fields. Probably report them, too, for example to catch changed JPA annotations on fields like a changed table name.

Also not sure which level to use. Warning? And in which category, should it be in binary or should there be a new category, like "semantics"?