test classes are not enhanced

Subj. When test @Entity-annotated class living somewhere under src/test, Ebean complains non-enhanced class.If I drag class into src/main, all is OK.

Another less annoying bug (or feature): plugin cannot process pure resource modules. E.g. I have module with sql scripts at src/main/resources/db/migration and blank src/main/java. And plugin fails with

```
Execution failed for task ':db-scripts:enhanceEbean'.
> java.lang.RuntimeException: File not found XXXX\db-scripts\build/classes/main/ currentDir:XXXX\db-scripts\.
```

Start with the enhanceEbean task and compare how it handles an @Entity-annotated class under src/test versus src/main. Reproduce the resource-only module using src/main/resources/db/migration and the reported build/classes/main error. Done means test entities are enhanced and a pure resource module completes without the missing-directory failure.

Written by the indexing model from the issue text.