[readme] clarify that a wrapper cookbook is needed for generating configs
Merge pull request #147 from needle-cookbooks/use-a-wrapper

[readme] clarify that a wrapper cookbook is needed for generating configs
[build] default sensu version of 0.9.12-3, init fixes
Merge pull request #149 from portertech/build

default sensu version of 0.9.12-3, init fixes