Convoy ignores dm.fs=xfs

[slavashvets]

Environment

• Convoy: v0.5.0
• Docker: 1.12.5-1.el7.centos (x86_64)
• OS: CentOS 7 (3.10.0-514.2.2.el7.x86_64)

Steps to reproduce

1. Download and unpack convoy
2. Create devices
3. Start Convoy daemon
   convoy daemon --drivers devicemapper --driver-opts dm.datadev=/dev/docker/volumedata --driver-opts dm.metadatadev=/dev/docker/volumemetadata --driver-opts dm.fs=xfs
4. Create volume:
   convoy create testxfs

Expected

The volume has XFS filesystem

Actual

# convoy inspect testxfs
{
        "Name": "testxfs",
        "Driver": "devicemapper",
        "MountPoint": "",
        "CreatedTime": "Fri Jan 20 13:57:11 +0300 2017",
        "DriverInfo": {
                "DevID": "27",
                "Device": "/dev/mapper/testxfs",
                "Driver": "devicemapper",
                "Filesystem": "ext4",
                "MountPoint": "",
                "Size": "107374182400",
                "VolumeCreatedAt": "Fri Jan 20 13:57:11 +0300 2017",
                "VolumeName": "testxfs"
        },
        "Snapshots": {}
}