Be more resilient to module initialization failure

[tfmorris]

Currently if any module loading/wiring/initialization fails, the entire server is disabled and just returns 500s with the initialization error. In some deployment scenarios, some of the modules might be ancillary not critical to the operation of the server (e.g. OpenRefine extensions). In this case it would be good if the server attempted to initialize the rest of the modules and continue operation.

This behavior should probably be controlled by a Butterfly property so that users can choose whether they want the historical behavior or the new behavior.

This was the second half of #13 which didn't get implemented.