Delete Requests: Deleted packages are not always AIPs

refs #7132

Packages being deleted are not always AIPs - get package type from request.
Fix raise to return
Migrations: Fix to upgrade from 0.4.0 migration

Fix 0004_v0_4_0 migration to match what's in the stable/0.4.0 branch.
Update the fedora and duracloud migrations to upgrade properly.
Preparing for 0.5.0 release

Updating version number in setup.py. Vendor Sword2 library.

Sword2 is listed in requirements as a github uri, which doesn't work from a
launchpad build server.  Add the sword2 tarball to lib and update the
requirements file to point to it.
Updating debian changelog and adding requirement

httplib2 is a dependency of sword2, and needs to be
added explicitly to the requirements file of the storage service
because sword2 source is included in the lib dir now, not downloaded.
Packaging: port to dh_virtualenv 0.8.x
Packaging: adjust dependencies

* Remove python-lxml dep, since we're using a different version from
  inside the virtualenv
* Add zlib1g-dev, to work around a yet-undiagnosed build issue on
  Trusty (building zlib fails to find zlib when linking)