WIP: Feature/docs

PyLTI documentation

Also visible at: http://pylti.readthedocs.org/en/feature-docs/
There are a lot of commented out lines in this. I know it can be handy to know what options there are, but it is easier to see changes and such if this only contains the items we set. This isn't for the review to pass, just a suggestion. You can choose to leave it as is.