XD-1807 Paging support for repositories

* Add utility class `PagingUtility` that returns the page implementation of
the given `Comparable` list
* Make `ModuleMetadata`, `ContainerAttributes` and `ModuleDefinition` of type
`Comparable`
* Update all the repositories `findAll(Pageable)` to use type specific
PageUtility's paged data
* Address review comments
** Add missing `Javadoc`
** Add the null check on `Pageable` at the PagingUtility
** Add assertion message on PagingUtility
** Use List.sublist while slicing
** Add PagingUtilityTests
XD-1838 FileSourceTest applies uses labels

SimpleFileSource & SimpleFileSink supports labels.
Code polishing based on review.
All fixtures updated based on code review.