MONGO_URI support

Fix transaction routine to support strings with { } but no values.
	This happens during installation with mongo errors.
Use MONGO_URI in calipso.js
Use mongo to store and load configuration.
Don't close and reopen mongo if MONGO_URI is supplied.
Change installation sequence if MONGO_URI is supplied.
Change screens for install_... templates if MONGO_URI is supplied.
Fix re-install for contentTypes to prevent unique key error in mongo.
Fix re-install for users to take over a previous admin account.
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