Add more languages

[wfscheper]

Currently xkcdpwd only supports English, though the framework is in place to support other languages.

Things to consider:

• Baked in dictionaries (like the English one) are easy to distribute and don't require configuraiton, but bloat the size of the binary.
• If we support user provided dictionaries, should we do any calculations to ensure that they're aren't using a dictionary that is too small?