Iniitial commit
Rakefile plus debug output configurable (use `DEBUG=2 rake` for example).
Made hash argument for CoRE::CoAP::Message.new omittable.
Restructurization.
Gemspec.
Merge remote-tracking branch 'cabo/henning'

Conflicts:
	Gemfile
	Rakefile
	coap.gemspec
	test/coap_test_helper.rb
	test/test_message.rb