Use Forwardable to delegate DurationChain#each to its 'units'.
Merge pull request #3 from jnbt/master

Time.now - Time.now isn't always zero (at least at my system)
Merge pull request #4 from jnbt/feature-use_forwardable_for_duration_chain

Use Forwardable to delegate DurationChain#each to its 'units'.
uninstall win32-console
Add travis.yml for CI