Rewrite request_spec.rb using rspec_given.
Refactor ICMP classes.
Updated TODO list.
Merge branch 'develop' into feature/refactor_icmp

Conflicts:
	pio.org
Updated TODO list.
Refactor ICMP::{Request,Reply}.
Refactori ICMP classes.
Updated ICMP examples.
Merge pull request #27 from trema/feature/refactor_icmp

Feature/refactor icmp