Allow an array of IP ranges

One can now specify a pool range as either a single string or an array
of string. An array simply inserts multiple range declarations in the
subnet conf file. Fixes #33
What's breaking? while the kitchen tests for the default and no_bags suites don't explicitly check the conf file syntax, the tests already included do pass.

I also forgot to commit an updated kitchen.yml file that includes an additional suite for multiple ranges. The tests and data_bag is there, however.