Add open-ils.cat.asset.copy.batch.delete as a streaming method.

Add open-ils.cat.asset.copy.batch.delete as a streaming method.

Use this method with appropriate callbacks in server/cat/util.js,
server/cat/copy_buckets.js, and circ/copy_status.js. This should
improve the performance of batch deletes in the client and allow
staff to delete more items at once.

This patch requires that working/user/dyrcona/lp939535 be applied
to OpenSRF in order to function properly.

Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>