XD-293 package-info.java in all packages

- Add missing `package-info.java` to all the packages
- Fix/Update javadoc
- Move `org.springframework.xd.dirt.XDRuntimeException`
to `org.springframework.xd.dirt.util.XDRuntimeException`

Code review changes

- Move `XDRuntimeException` to DIRT base package again
  - Add package-info.java

Fix EOF line at package-info.java files

Fix typo in javadoc