[SRU xenial/yakkety/zesty] LP#1640109 -- hv_set_ifconfig script parsing fails for certain configuration

[Andy Whitcroft]

Reporter found issues with the handling of DHCP configured interfaces.
The script simply craters and does not setup the configuration.  Following
this email are two patches: the first fixes this issue so that requests
for a DHCP configuration result in a properly formed stanza; the second
fixes potential loss of a final stanza if it is the last one in the file.

Proposing for SRU to xenial, yakkety, and by implication zenial.

-apw