Fixes indents of templates and bumps YUI dependencies

This PR fixes #288. This problem is due to `Y.Handlebars` have been upgraded from v1.x to v2.0.0 since YUI 3.18.0.

Handlebars v2.0.0 have been changed the handling of indents to matches to the Mustache specs.
https://github.com/wycats/handlebars.js/blob/master/release-notes.md

Therefore, it fixes indents of templates and I'd like to make clear YUIDoc uses Handlebars v2.0.0 by depending on YUI 3.18.1 or later.