CORE: fixed optimization of getData() methods

- Fixed SQL when selecting user required attributes
- Method for creating string with list of IDs changed
  from handling only Users to all PerunBeans.
- Methods getRequiredAttributes() for list of users now return
  HashMap<User, List<Attribute>> instead of HashMap<Integer, List<Attribute>>,
  to be the same as member-like methods.
- Added missing authorization on retrieved attributes for new
  getRequiredAttributes() methods.
- Updated javadoc to respect above changes.
- When resolving authorization on attributes, always load user and
  facility (if necessary by method). Don't do it for each retrieved attribute.
  Like this data are loaded everytime, but only once (not per each attribute).
- Fixed typos on various places, removed some whitespace.
- Fixed indentation of ServicesManagerEntryIntegrationTest.