Limit slugs to 150 characters

Use the babosa gem to remove punctuation and apply the safe truncate
when we override `normalize_friendly_id`

https://www.pivotaltracker.com/story/show/47813037
https://www.pivotaltracker.com/story/show/32487033

If we want to fix the boken links on the flat site - we will need to run a separate migration to regenerate the published slugs over this length and add in the redirects, but this will prevent the issue from growing at the moment we have around 344 slugs which will need redirects which are over the limit (and published)