Add integration tests that test common markup on a page

[natikgadzhi]

The idea is to have a very simple integration test that would verify that Notoma Convert works as expected.

To make this, I can:

• Create a simple test structure, like tests/integration/convert/
• Add a fixture of a Markdown file that I convert with Notoma manually and review it's correctness, we'll use this as reference.
• Write a simple shell script as a test that would invoke notoma convert, use the key and the blog database from env variables and put the output in the out directory.
• Compare the out/reference.md to fixtures/reference.md. If they're different, then something is broken ;)