Build: Test node.js 0.12 and io.js on Travis CI, too.
Build: Test node.js 0.12 and io.js on Travis CI, too.

Closes #50

jzaefferer/grunt-html,jzaefferer/grunt-html,jzaefferer/grunt-html,wesjones/grunt-html,wesjones/grunt-html,wesjones/grunt-html