[webui] Disable browser autocomplete on sign up form
[webui] Don't reference config options in environment files...
[backend] Add Suite/Codename to Release, add SHA1+SHA256 checksums, don't add checksum of the partial Release file itself
[backend] Clean up emulator build invocation code

For the emulator case, a lot of the options were not passed
down to the build invocation, like for example the filesystem
to create, which defaulted to the site-wide filesystem instead
of the worker-defined filesystem type.

The one two differences we want to have is to disable statistics
(as they slow down the emulated build) and use a different way
to invoke the emulator mode, otherwise the rest should be passed
down as is.
[backend] Avoid failing job when Build.pm cannot be imported

Thats most likely a host problem (cpio not working,
network conflicts), don't fail the job
[backend] Clean up vm type setting

$vm awkwardly had a leading space in some cases, which
caused invocations that were not passed through the shell
to fail (as the leading space was then part of the argument).

Also, half of the code compared the vm incorrectly, consequently
also failed to detect vm type properly.

Fixes killing of running jobs amongst other things for KVM and
ZVM.