Fixes #107 ("Hanlon subnet" check fails under Tomcat)

When Hanlon is deployed under Tomcat, calls to `Facter.value(:kernel)` return an empty string. As a result, attempts to get the list of available interfaces, a value from a specific interface, or the output containing the text from a single interface using Facter all return either `nil` or an empty string. This commit monkey-patches the Facter::Util::IP module (within the Hanlon::WebService::Utils module) so that the correct values are returned when the `Facter::Util::IP.get_interfaces` or `Facter::Util::IP.get_interface_value(interface, label)` methods are called (even when Hanlon is deployed under Tomcat)