dvr.js: Add 'all' option to paging length to address limitations of only...

... sorting current page

This is in response to the conversation in PR #399 regarding only being able to sort the current page and not the whole data set. It simply adds an "all" option to the page length (actually, a page length of 9,999,999,999 - that should be big enough for most user) that the user can select prior to sort.