Fix 'Load More'

* Pager is using partial find option to find an index, this results
  the storage returning wrong index with sortby option

* timestamp is not a UUID, should not have -id suffix in parameter

It's really hard to debug the code with these identical params:
pager-dir, offset-dir, pager-offset, offset-id, offset, offset-elastic,
a future refactor is preferred

Change-Id: Ifa1fadab137dfef75fc5b9cc6e03e0f01f8ea15f