ChangeList: Unify query and next

The next method doesn't really get a "next" page of results because
there is no "previous" page of results to compare to. Rather, it gets
a single page of results, with a specified start and count. Rename it
to avoid confusion.

Once we do this, it is clear that the only difference between the old
query method and this one is that the old method had a default set of
parameters. Reorder the parameters and delegate to make this clearer.

Change-Id: Iaf8ce9e4ecb6842aed23527e5838361d6f67bbe4
3 files changed