split on , for debian packages to handle multiple packages owning the sa...

Currently I get multiple packages back from the debian implementation as a comma separated list

```
twin% perl -Ilib -MYAML -MAlien::Packages -E 'print YAML::Dump({Alien::Packages->new->list_fileowners("/bin")})'
---
/bin:
  - Package: 'login, tar, sysvinit-utils, bzip2, fuse, mount, ntfs-3g, bash, dash, grep, gzip, hostname, busybox, csh, xserver-xorg-input-vmmouse, initscripts, debianutils, console-setup, kmod, psmisc, base-files, sed, util-linux, coreutils, bsdutils, netcat-openbsd, ed, iputils-ping, net-tools, nano, netcat-traditional, less, fgetty, zsh, acl, tcsh, console-tools, iproute, cpio, procps, pax, live-tools'
    PkgType: dpkg
```

With this patch, I get it back as a list of hashes, which is what I think is intended from the documenttion:

```
twin% perl -Ilib -MYAML -MAlien::Packages -E 'print YAML::Dump(Alien::Packages->new->list_fileowners("/bin"))'
--- /bin
---
- Package: login
  PkgType: dpkg
- Package: tar
  PkgType: dpkg
- Package: sysvinit-utils
  PkgType: dpkg
- Package: bzip2
  PkgType: dpkg
- Package: fuse
  PkgType: dpkg
- Package: mount
...
```