Add clear_cache cli command. fix #98

Allow all config options to be specified in realms-wiki.json

Add gravatar icons to history

Add an icon and sort column for pages/dirs in the index

Implements a tree view index

Support getting indexs of subdirs

Fix rebuild_index to use full path of page when indexing.

Enable caching of wiki pages

Tweak the rules for to_canonical to better handle subdirs

Preliminary subdirectory support. refs #50

Auth

define tokengetter for each provider

auth submodules are registered with initialized
check if auth.local is loaded before accessing registration route
check DB_URI before attempt to create db

oauth authorize callback to use absolute url, needed by Facebook