[api] Take sub-packages into account (dependecy check)

Dependencies are checked in status method, but sub-packages of submitted
package are not taken into account and are reported incorrectly as
missing dependencies. This patch fixes it.
[webui] Handle the group case correctly for the set_bugowner request
[dist] add vfat kernel module for kvm workers
[api] simple test and fixture for _statistics route
[backend] fix minor typo
[backend] make getsslcert also work the first time it is called
[backend] don't commit certs when the signkey is "1"
[backend] switch to RSA@2048 for new signing keys. WARNING: sign must be at least 2.1.5.1 for this to work
[backend] tweak sslcert retrival again to bring to more in line with the signkey handling
[backend] fix spurious next statement in signer
[backend] don't retry signing if the cpio.rsasign is bad
[backend] Fix error message in product converter

ERROR: No such archset HASH(0x28d5080) is not a useful error message.
[backend] do always use package release number as product provides. This basically makes the usage
          of explicit product release numbers not possible anymore, but it seems every product just
          worked around this anyway.
[backend] refactor so that we no longer do multiple commits for key manipulations
[backend] bs_signer: refactor signing code, no functual changes
[backend] add $BSConfig::dispatch_constraint hook (i.e. hack) for hard constraints
[api][webui] support local webui's speaking to a remote api anonymously using /public/configuration route.
make it possible to exclude specific sandboxes and hostlabels in constraints
Restructure the user home page
Make users reall editable through the API