Upgrade to bonecp 0.8.0-dcache1

In addition to the changes in 0.8.0.RELEASE, this version adds the
fixes in the following two pull requests:

https://github.com/wwadge/bonecp/pull/18
https://github.com/wwadge/bonecp/pull/19

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6186/