nut 2.7.2 (new formula)

nut, also known as network UPS tools, is a set of tools for
communicating with UPSes, PDUs and solar power controllers. It provides
a daemon, logging and drivers. It communicated over serial lines, USB,
SNMP, IPMI and via HTTP. The name 'nut' is not particularly descriptive
and does not help users find UPS tools, but it matches the Debian
package nomenclature.

This pull request requires the 'powerline' new formula pull request.
Can this test be modified to do something more substantial than e.g. `--version` or `--help`? See `cmake.rb` for an example of an application formula with a good test and `tinyxml2.rb` for an example of a library formula with a good test. Thanks!