Add jslint hints and fix styling
Fix formatting for rfc822date, introduce isodate

This makes functions returning RFC-822 dates actually return them in proper
format. Previously they were incorrectly returning ISO-formatted dates.
RFC-822 dates are used for the recently-introduced RSS feeds. As Atom feeds
do need ISO-formatted dates, new "isodate" functions have been added.
Fix missing "this" in Page.relpath()