Description of problem:
virt-inspector xpath query should output a neat format of the query element.

This problem also exist in RHEL6.7 and RHEL7.1. 


Version-Release number of selected component (if applicable):
libguestfs-tools-c-1.29.33-1.fc22.x86_64


How reproducible:
100%


Steps to Reproduce:
1. Prepare a guest image, such as Fedora20
2. Run the following command: 
# virt-inspector -a Fedora-20.raw |virt-inspector --xpath '//mountpoints'
<mountpoints>
          <mountpoint dev="/dev/fedora_dhcp-66-103-65/root">/</mountpoint>
          <mountpoint dev="/dev/sda1">/boot</mountpoint>
        </mountpoints>


Actual results:
As above


Expected results:
<mountpoints>
          <mountpoint dev="/dev/fedora_dhcp-66-103-65/root">/</mountpoint>
          <mountpoint dev="/dev/sda1">/boot</mountpoint>
</mountpoints>


Additional info:
The output format is also not neat when query other elements, such as: filesystem, operatingsystem, etc.