[respect-network-flag-#75464982)]: create IP pool

An IP pool provides allocation and releasing of individual IP
addresses from a given range.

Add flag parsing for net fence

Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com>
[respect-network-flag-#75464982]: Support creating IP Pool from CIDR

The network and broadcast addresses should not be allocated as they
are not valid IP addresses.
[(no branch, rebasing respect-network-flag-#75464982)]: [(no branch, rebasing respect-network-flag-#75464982)]: [respect-network-flag-#75464982]: [respect-network-flag-#75464982]: wip - try using ips rather than 30 networks

Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com>
[(no branch, rebasing respect-network-flag-#75464982)]: [(no branch, rebasing respect-network-flag-#75464982)]: [respect-network-flag-#75464982]: Prevent test pollution by using new tmpdir each time

Signed-off-by: Julian Friedman <julz.friedman@uk.ibm.com>