builddeb: ignore vcs and build results This one is a no-brainer. Previously, if you tried to build a deb on ubuntu, it would try to diff files in the .hg store. These flags prevent that.

builddeb: copy over .gz and .dsc files We were forgetting to copy over the signature (if it exists) and the zipped diff, so let's do that.

builddeb: ignore errors about find not finding files The debuild command may output less files than we explicitly list so let's not error out if none exist.