Merge pull request #656 from BramChen/master

Update chinese translations
Remove the cat from the server architecture diagram
Add environment variables for locating plugins

Start of fixing #531 (we still need to deal with
TIDDLYWIKI_EDITION_PATH)
Add support for TIDDLYWIKI_EDITION_PATH
Docs for environment variable support

Fixes #531
Remove extraneous tag

Tiddlers tagged “resources” show up in the Community tiddler, which we
don’t want here.
Refactoring plugin loading on Node.js
Allow arbitrary fields in plugin.info files

Fixes #642