Webtiles: Add startup check for config.password_db

Warn if we're going to create it, and fail early if we can't.
Webtiles: init_player_program improvements

* Make it optional
* End-user message on failure should be more generic
Webtiles: move init_logging to conf.py so we can log earlier
Webtiles: get rid of 'from util import *'
Webtiles: Add some debug logging to check_config
Webtiles: improve process_handler start/stop logging
Webtiles: Add permanent fallback for maybe_minify

Currently, maybe_minify looks for minified js files every time and
silently falls back to non-minified. This change permanently falls back
to non-minified after one lookup failure and logs a warning.
Webtiles: allow overriding templates

Without modifying tracked files, that is. The template loader will try
to load a given filename, eg banner.html, but fall back to eg
banner.html.default if the former doesn't exist.
Webtiles: let get_rc handle nonexistent rc file