[zaphod-v0.3]: Fix incorrect reference to 'iputils' in comments.

SYNOPSIS
[modified]m42/test/test_iputil.py: Change 'iputils' to 'iputil' in comments.
[zaphod-v0.3]: Add comments for save/restore dummy functions in test_mac2ip.

SYNOPSIS
[modified]m42/test/test_iputil.py: Comments for save/restore in test_mac2ip.
[zaphod-v0.3]: Implemented ping subnet.

SYNOPSIS
[modified]m42/iputil.py: Implemented pingsubnet.
[modified]m42/test/test_iputil.py: Test for pingsubnet.

DETAILS
Pingsubnet invokes fping to ping all the IP addresses in a subnet. This
will be used (indirectly) by mac2ip to force the host OS to cache
a bridged VMs MAC and IP address its ARP table from which the MAC-to-IP
mapping of the VM can be inferred.
[zaphod-v0.3]: Make test input more consistent.

SYNOPSIS
[modified]m42/iputil.py: Sort physical_interfaces output for more predictablity.
[modified]m42/test/test_iputil.py: Change test input easier for ping testing.

DETAILS
Changed the test input so that testing of code that involves combining
arp table output, ping output and interface selection is possible. Now
all dummy functions return consistent output. The test code has been
modifed to expect different values to be returned from calling the
functions being tested.
[zaphod-v0.3]: Implemented pingallsubnets

SYNOPSIS
[modified]m42/iputil.py: pingallsubnets: ping all subnets of a given interface.
[modified]m42/test/test_iputil.py: Unit tests for pingallsubnets.

DETAILS
pingallsubnets pings every address of every network associated with a given
host interface. This is used help populate the ARP table of the host.
[zaphod-v0.3]: Implemented _bridged_host_adapter

SYNOPSIS
[modified]m42/zaphod.py: Implemented _bridged_host_adapter
[modified]m42/test/test_zaphod.py:  Unit test for _bridged_host_adapter.

DETAILS
Implemented Zaphod._bridged_host_adapter that returns the host adapter
that a VM's virtual network adapter is bridged to.
[zaphod-v0.3]: Implemented macaddress_long_to_short

SYNOPSIS
[modified]m42/iputil.py: Implemented macaddress_long_to_short.
[modified]m42/test/test_iputil.py:  Unit test for macaddress_long_to_short.

DETAILS
macaddress_long_to_short converts a MAC address in long format:
xx:xx:xx:xx:xx:xx (as reported by arp -a) to a short format: XXXXXXXXXXXX
as reported by VirtualBox.
[zaphod-v0.3]: Ping all hosts on subnet before reading arp table.

SYNOPSIS
[modified]m42/iputil.py: Ping all hosts on subnet. Use macaddress_long_to_short.
[modified]m42/test/test_iputil.py: 'Smarter' dummy functions.

DETAILS
mac2ip now pings the subnets of the interface being probed for MAC to IP
translation to force the ARP table to be populated with the IP and MAC
of the VM whose IP address is being sought.

test_iputil.py now implements a dummy command shell function that
returns the outupt that is expected of it based on the input command.
This allows it dummy output that needs to be different based on the
command that is passed to it.
[zaphod-v0.3]: Modify call to mac2ip.

SYNOPSIS
[modified]m42/zaphod.py: mac2ip now requires a host_adapter to probe.

DETAILS
Modified zaphod to pass the host adapter name to mac2ip so that subnets
on the host adapter can be probed to get IP addresses of bridged VMs.