initial implementation of request forwarding, cookies set from dbwriter are still not being properly passed through - issue #460

fix typo: complete_email_addition writes the database and hence should be forwarded to dbwriter - issue #460

improve per-process informational debug output about what WSAPIs are supported, their requirements, and how they are handled (forwarded or handled locally?) - issue #460

This reverts commit 019857e3.

don't log an error level message if the json database does't exist (yet), just a debug.  closes #509

add the dbwriter process.   it's not yet hooked up, but starts up and runs, and included in health check.

reorganize browserid process - break out view serving and wsapi handling.  preparation for dbwriter split.  issue #460

rework mysql connection logic: fixes create_schema flag and properly reconnects to database.  closes #548

everything else is filtered.  Things like Content-Encoding shouldn't be blindly
forwarded.

Also when forwarding responses,  ensure proper casing of headers.

issue #460

ensure that the internal code_update URL is hit *precisely* to reduce the risk of improperly configured servers and sloppy expressjs routing letting just anyone reboot a server.  bug #699171

implement graceful process shutdown, and clear logging as to the reason why processes are terminating.  include winston handling of uncaught exceptions.  this all goes into a library that all of our processes use.  closes #529

in production (dev/beta/prod) use a more conventional logging format that includes timestamps.  closes #234

ensure that the internal code_update URL is hit *precisely* to reduce the risk of improperly configured servers and sloppy expressjs routing letting just anyone reboot a server.  bug #699171

implement graceful process shutdown, and clear logging as to the reason why processes are terminating.  include winston handling of uncaught exceptions.  this all goes into a library that all of our processes use.  closes #529

in production (dev/beta/prod) use a more conventional logging format that includes timestamps.  closes #234

temporarily disable relay to keysigner until http forwarding logic is figured out/fixed - issue #460

add back an erroneously removed check in cert_key to verify that the authenticated user has verified the email which they are trying to get a certificate for - issue #460

fix a bug in validation library.  if we find a parameter validation error, don't call the next handler in the onion ring, fail out

break 'checkParams' feature out into a separate file so it can be shared by multiple processes - issue #460

implement throttling on outbound emails: don't send emails to the same address more than once per minute - issue #430