Added "Load More Files" button to load certain number of files each time to improve performance and number of files of the study to the page.
Added several methods  to implement the business logic of loading certain number of files each time to improve performance.
Added method to retrieve ordered file ids by study version.
Added method to retrieve ordered file metadata where file ids in a file id list.
Merge branch 'develop' of https://github.com/IQSS/dvn.git into develop