Lint for UpperCamelCase classes intended as metadata annotations (Style Guide).

**DO** use UpperCamelCase names for classes intended to be used in metadata annotations.

If the annotation takes no parameters, you might want to create a lowerCamelCase constant for it.

**GOOD:**

```
@Foo(anArg)
class A { ... }

@Foo()
class B { ... }

@foo
class C { ... }
```
