Integrate user manual and install guides into KA Lite

Not mergable yet, needs polish

Foundation has been laid though, to do list includes:

1. Migration for the new user resource model
2. Navigation and styling for user resources and user resource detail page
3. Linking from the main KA Lite page in the appropriate places (not just in download section) 

and other things I'm sure I'll think of tomorrow 
@jamalex see these three url schemas -- the tricky bit for me was how best to do user_guide latest. I thought maybe there would be a nicer way to do it just passing in an extra parameter to user_guide_detail but couldn't figure it out in a short period of time so wrote another view entirely.