[JIRA-81] Web UI Pagination

add pagination to in memory files' view in web UI, only show 20 files a page. 

without pagination, when there are too many files in memory, it will take a long time to render the 'in memory files' page.
Having Java code in JSP (scriplets) is highly discouraged because it mix MVC logic and will make it harder to debug and dev later on.

Could you try to move the server logic to Java bean with request context?