v2v: -i disk: Don't fail if filename has no extension.

Unhelpfully, Filename.chop_extension throws an exception if the
filename has no extension (instead of just returning the filename).
Therefore the -i disk option would fail if you passed any filename
that didn't have an extension.
v2v: -i disk: Add a clearer error message if the disk doesn't exist or is not readable.
v2v: R_OK is in Unix module
daemon: make aug_close cleanup available for all

Just code motion, no behaviour changes.
v2v: -i libvirt: Check the domain is not running (RHBZ#1138586).

It will print an error like this:

  virt-v2v: error: internal error: invalid argument: libvirt domain 'windows'
  is running, it must be shut down in order to perform virt-v2v conversion

This only works for libvirt domains, and is explicitly disabled for
test:/// URIs since these domains are always "running", but we use
these URIs for testing.
v2v: When locating initramfs, ignore kdump initramfs images (RHBZ#1138184).

Thanks: Tingting Zheng.
v2v: -i libvirt, -i libvirtxml: Print libvirt XML when debugging.
daemon: add a way to check for the version of augeas

Query augeas for its version when required, i.e. only once when using
the new augeas_is_version function.
appliance: daemon: import and use upstream shadow lens

Import the upstream lens for the shadow file, just with a different
identifier and not matching /etc/shadow by default. Instead, apply a
transformation to have it match /etc/shadow only if the version of
augeas is at least 1.2.1 [1].

[1] While the last upstream version is 1.2.0, all the development seems
to happen in master, so whatever the next version is going to be
numbered (e.g. 1.2.1 or 1.3.0), the check will be fine anyway.
sysprep: remove comment and notes about /etc/shadow lens

We are either using the upstream lens, or our copy of it, to handle
/etc/shadow, so now removing entries from it works.
customize: use augeas to change passwords

Make use of augeas to load and edit /etc/shadow, now that we have
(either from upstream or by ourselves) a lens handling it.
appliance: Add guestfs_shadow.aug to EXTRA_DIST.

Fixes commit 61917136f5ad5efe30502f46f1adf60c20f15c97.
Version 1.27.38.
RHEL 7: Emphasize libguestfs-winsupport package (RHBZ#627468).

This RHEL-only patch changes the error messages when the
inspection code cannot find an operating system inside the guest
image.  For a Windows guest this may happen because the user has not
installed the separate 'libguestfs-winsupport' package.  Therefore we
emphasize that the user may need to install this package.

Notes:

(1) In RHEL there are two pieces of inspection code, the old Perl code
(deprecated upstream) and the new C core inspection API.  Therefore
this patch has to touch two places with essentially the same change.

(2) This patch doesn't try to be clever and detect if it was a Windows
guest.  This should reduce the chance of failure.

Output from (Perl) virt-inspector now looks like this:

 $ virt-inspector disk.img
 No operating system could be detected inside this disk image.

 This may be because the file is not a disk image, or is not a virtual machine
 image, or because the OS type is not understood by virt-inspector.

 If you feel this is an error, please file a bug report including as much
 information about the disk image as possible.

 RHEL notice
 -------------
 libguestfs will return this error for Microsoft Windows guests if the
 separate 'libguestfs-winsupport' package is not installed. If the
 guest is running Microsoft Windows, please try again after installing
 'libguestfs-winsupport'.

Output from guestfish (ie. C core inspection API) now looks like this:

 $ guestfish -i disk.img
 guestfish: no operating system was found on this disk

 RHEL notice
 -------------
 libguestfs will return this error for Microsoft Windows guests if the
 separate 'libguestfs-winsupport' package is not installed. If the
 guest is running Microsoft Windows, please try again after installing
 'libguestfs-winsupport'.
RHEL 7: Remove libguestfs live (RHBZ#798980).

This isn't supported in RHEL 7.
RHEL 7: Remove 9p APIs from RHEL (RHBZ#921710).
RHEL 7: Disable unsupported remote drive protocols (RHBZ#962113).

This disables support for unsupported remote drive protocols:

 * ftp
 * ftps
 * http
 * https
 * tftp
 * gluster
 * iscsi
 * rbd
 * sheepdog
 * ssh

Note 'nbd' is not disabled, and of course 'file' works.

We hope to gradually add some of these back over the lifetime of RHEL 7.