Threaded ICMP with tests, response_data, external runs with ruby 1.8.7, plus ....

* Add threading support for ICMP and test as root as per https://www.ruby-forum.com/topic/146116;
* Support external with ruby 1.8.7 where the external command returns "N% [packet ]loss";
* Add response_data for most types (icmp, wmi not done) Based on rigor/master;
* Exclude tests that don't work with non mri rubies;
  * jruby: Excludes UDP, ICMP, TCP
  * rbx: Excludes ICMP
* Note in README that ICMP doesn't resolve hostnames;
* Use 127.0.0.1 rather than 192.168.0.1;