Escape string quotes

[Lyla-Fischer]

First draft of string escaping. I put the appropriate code in the three places where there seems to be repeated code, and I think that I should probably take the opportunity to refactor that code to be more DRY. Submitting this as the quick-and-dirty fix, though.

Addresses #7

[Lyla-Fischer]

lol - you used to be able to get away with force-pushing on pull requests without Github commenting on it.

After trying to enter the resulting mutation into dgraph, I found out that I was misformating it (you're not supposed to escape single-quotes), so I removed that part of the escaping.

[Lyla-Fischer]

I'm embarrassed at the force-pushing, but in other projects, that was preferred to having a commit history with a separate commit for every mistake made, at least when we were in the pull request review stage. Let me know if you prefer something different for your project.

[ahopkins]

My preferred method would be a WIP: prefix to the PR name. And commit away. At the end when it is ready a rebase -i to cleanup anything unnecessary.

[Lyla-Fischer]

The tests pass now, and I tested the output in dgraph to make sure that it runs.

[ahopkins]

nice. Any more work on this? Can I merge? If I have a chance to setup Travis CI this week I will. It might have to wait till next week. I will be at PyCon Israel this week.

[Lyla-Fischer]

Ya, I think it's ready to go.