Change region declaration syntax. Closes gh-619.

As i’ve mentioned, old syntax is confusing.

I’ve made automatic converter from old syntax to new to avoid spending a lot of time converting it manually: https://gist.github.com/paulmillr/5891455, so upgrading to new chaplin will be fast.

Please review @mehcode @molily @knuton. I think this is the last change for 0.10.