Add static code analysis

[satwikkansal]

Now that the project has Travis integration, I think we can use a static code analysis tool like coala which can help in detecting errors like following upfront,

• Markdown linting errors (and the linting errors in the code inside the markdown)
• Invalid or broken links (like TOC, references, etc)
• Grammar checks

The commands to perfrom such checks can be added to Travis as well as pre-commit hooks (if the contributor likes), and will help in reducing future errors.

[josephwon0310]

I would love this patch to go live asap. I'm not sure whether it's the Korean encoding not working with MD or it's just some under the hood inconsistency that breaks TOC links for me, but this will help with most of the problems.