These changes create a dev org in the database on startup.
They also plumb through a dev-org-id flag that allows specifying a chosen org ID in dev mode.
The logic will allow us to let people specify a default org ID in the config file too, although currently that's not enabled.
Several other improvements were made as well:
* Consolidation of some code from across the server commands
* Plumbing shutdownch through so we can use it for canceling contexts during startup
This was copied from Vault code but shouldn't be necessary any more as a
change in hclog a while back meant that derived loggers share the log
level of the parent.
Jeff Mitchell