Fixing issues #79, #80, and #82.

[nicovalencia]

• closes Latest grunt-mocha module requires grunt update. #79 Latest grunt-mocha module requires grunt update.
• closes Grunt lint task needs to be updated with Grunt upgrade. #80 Grunt lint task needs to be updated with Grunt upgrade.
• closes Adding multiple titles/headers with the same content produces invalid markup. #82 Adding multiple titles/headers with the same content produces invalid markup.

> grunt test

Running "simplemocha:all" (simplemocha) task
path.existsSync is now called `fs.existsSync`.

  .........................................................

  ✔ 57 tests complete (44ms)


Running "jshint:src" (jshint) task
>> 5 files lint free.

Running "jshint:test" (jshint) task
>> 1 file lint free.