add btrfs and zfs recognition to gpart

[Karl-Philipp Richter]

`gpart` provides the possibility to recognize partition with pluggable modules. It'd be great to develop such and provide them by default in the `gpart` package (or in separate packages `gpart-btrfs`, `gpart-zfs` or `gpart-modules`).

It seems like the development stopped at version 0.1f in 2001[1] although 0.1h is provided since before trusty. It be good if Ubuntu would provide a possibility to recognize partitions on disks with a broken partition table. As long as there's no alternative, development of `gpart` is a viable option, I guess.

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[1] http://www.brzitwa.de/mb/gpart/index.html

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: gpart 0.1h-11
ProcVersionSignature: Ubuntu 3.13.0-37.64-generic 3.13.11.7
Uname: Linux 3.13.0-37-generic x86_64
NonfreeKernelModules: openafs zfs zunicode zavl zcommon znvpair
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Oct 17 21:53:20 2014
Dependencies:
 gcc-4.9-base 4.9.1-0ubuntu1
 libc6 2.19-0ubuntu6.3
 libgcc1 1:4.9.1-0ubuntu1
 multiarch-support 2.19-0ubuntu6.3
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-03-01 (230 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
SourcePackage: gpart
UpgradeStatus: Upgraded to trusty on 2014-06-19 (120 days ago)

[Baruch Even (baruche)]

I've collated multiple patches for gpart and just a few days ago got a patch to add btrfs support. I released 0.3 with this new support. Hopefully it will go into Debian at some point in the near future and from there can flow to Ubuntu as well.