Fix for UTF-8 encoding error (and some other tweaks)

Hey there,

This is the first time I've even tried the whole 'pull request' thing, so excuse me if I don't know the conventions!

Anyway, I found your code very useful, and have made a few tweaks I thought might by worth merging into the main repository. (I found your code through the ChemSpider website.)

I hit some error messages related to encodings when retrieving information from the database, which were fixed by explicitly encoding all the retrieved text into UTF-8.

I've also added the __init__.py to allow it to be imported as a module, and have moved the private token definition into a separate (git ignored) file, to make storing that easier inside the repository.

Hope that all makes sense!

Cheers,

Nick Fyson