our special error handler for json requests would turn all exceptions
into 500s - removed it. now the rescue_responses can do their thing
again.

We'll only use the master branch for development from now on.

exists? is deprecated in ruby 2.1

CouchRest > 1.2 does not use RestClient anymore. So we should not try to
catch its errors.

We had rewritten use_database so it would not crash the entire app
if couch was not available at the time of initialization.

couchrest now moved on and only sets the database name on use_database.
The database will only be queried once it is really needed. So pretty
much exactly what we want.

Our hack instead caused quite a bit of problems as it would still
initialize the database during start. This way the app would remain
in an invalid state even when couch came back.

the Warden::SessionSerializer was not getting loaded at all because we had a file by the same name. We want it to get loaded and be patched instead.

It removed most of the reduce functions... really not what we wanted

Also move complex identity views into js designs.
Includes test.

Here's how you would query it from outside rails:
```
$ curl
'localhost:5984/identities/_design/Identity/_view/cert_fingerprints_by_expiry?startkey="2014-07-05"'
{"total_rows":4,"offset":1,"rows":[
{"id":"6c9091d4f13eaeaa6062c9d0528fd34d","key":"2014-07-05","value":"fingerprint"},
{"id":"6f3aa93828b4f6978d551f2623b9d103","key":"2014-07-05","value":"fingerprint"},
{"id":"b6cafacfa65042679691cd5065fb19e3","key":"2014-07-07","value":"fp"}
]}
```

Note that the expiry will be used as the key. So you should use the
current data (or yesterday) as the startkey to get all fingerprints that
have not expired yet.

The fingerprint itself is in the value. No need to include docs.