Removed IP addresses from comments and from most other listing pages.
IPs take up a lot of space in many places (especially IPv6 addresses),
and in most of these pages they're rarely useful for catching
sockpuppets.
Fineprint text was variously styled with `.info`, `.tn`, `.hint`, or
`.cost-footnote` css classes. Standardize on `.fineprint` instead. Use
`.hint` only for form hints and `.tn` only for <tn> tags in translation
notes.
Incidentally changes the font size of form hints to 0.8em (was 0.7em)
and the color of fineprint to #888 (was #AAA or #666).
Sends automated dmails from `Danbooru.config.system_user`, rather than
whichever user is performing the action happens to be (usually User.admins.first).
Also adds a notice in the view that the dmail was automated.
