Fix batch summary to use the api

Fix batch summary to use the api

In looking at @colemanw's work to clean up the retrieve function it
turned out that in at least one place NULL is being passed to Batch::retrieve

Since I dug into that 1 place I fixed it to use v4 api (it is
the screen accessed after creating a new accounting batch
from contribution->accounting batches->new batch)

However, it seems safer to continue to accept NULL