Remove accept predicates on json routes

By having accept predicates for 'text/html' routes and leaving them
off for json routes the html routes becomes more specific matches.
In many cases, crawlers or scrapers, such as the Facebook thumbnail
and summary generator, may send "Accept: */*", or at least fail to
include the wildcard MIME type with lower priority than an explicit
'text/html'. In this case, the previous configuration would return
JSON.