This changes what displays in the NodeInfo, and in the future might be
used for other things.

This is almost all of T541

This allows admin to edit these pages from the web, using Markdown. It
also dynamically loads information on those pages now, and makes loading
`pages` templates a little easier to find in the code / more explicit.

It requires this new schema change:

CREATE TABLE IF NOT EXISTS `appcontent` (
  `id` varchar(36) NOT NULL,
  `content` mediumtext CHARACTER SET utf8 COLLATE utf8_bin NOT NULL,
  `updated` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

This closes T533

Start of T538

Usage: writefreely --reset-pass <username>

This closes #25, closes T534