feature: improved safe volume formatting

This change beefs up the safety features around formatting volumes, and introduces a
chefspec unit test for the the volumes cookbook.

With this change, one should be able to use ironfan to safely create
formatted ebs mounted drives without the use of the "blank_xfs"
snapshot.

Squashed commit of the following:

commit 2d5e264c8a33466caec921ef125d23ff3ba313dd
Author: Chris Howe <howech@infochimps.com>
Date:   Wed Apr 2 13:04:13 2014 -0500

    Added a chefspec style unit test for volume formatting, mounting, and resizing operations.

    raid striping operations are not currently under test.

    Change-Id: Id6aca70be1e0742f689ba96c439dacac53791553

commit af6bc96b7017cdbb60fca4e5f2164b694a34bcdd
Author: Chris Howe <howech@infochimps.com>
Date:   Wed Apr 2 12:59:02 2014 -0500

    Added a guard to the format resource which will keep us from accidentally
    reformatting over a file system of the same type. Note that "blkid" is
    a more reliable way to check file system types than "file -s".

    Change-Id: Ic2a30c0b0bc02bcd4ace5474de9b727af7bd742d

commit 81c70b15ed28060c5ca0e964d391d6fcb7802b8d
Author: Chris Howe <howech@infochimps.com>
Date:   Wed Apr 2 12:55:22 2014 -0500

    Simplified the operation of the simple_volume object.
    For testing purpoeses, it now does everything from ohai discoveries and
    other node attibutes. Allowing this object to directly touch the filesystem
    to look for device files, and to check file system attributes makes it
    extraordinarily difficult to test.

    Change-Id: I866df67a4a722fdaf01ac4394b04e3a80fa1c714

commit 3f0b5e10acc9ae3198bd2841f15f7006b6e91e5b
Author: Chris Howe <howech@infochimps.com>
Date:   Wed Apr 2 12:54:54 2014 -0500

    bumped cookbook version

    Change-Id: I26b1dff0f6a6a30585561feac8f35a18d7f215b2

Change-Id: Ifa253c91e116e9dca7cf746088b4649ad5ea5b48
Merge "feature: improved safe volume formatting"