Add statsd metric for looking up /.well-known/browserid

fixes #1704
report success and failure cases separately for fetch_well_known and deep_fetch_well_known statsd metrics.
Send along the start time and timestamp with the .well-known statsd metrics.
Place elapsed time into its own field in the log

```
{"elapsed":246,"level":"info","message":"elapsed_time.deep_fetch_well_known.error","timestamp":"2013-10-16T13:24:43.255Z"}
```
Merge pull request #3980 from seanmonstar/express-use

use express mounting, kill connect-cookie-session

After @seanmonstar's updates to fix the requestKey problem, all good.

Selenium tests pass, backend tests pass, front end tests pass.  r+
remove obsolete reference to env.ZERIGO_DNS_KEY and env.PERSONA_DEPLOY_DNS_KEY; add a way to specify default domain with env.PERSONA_DEPLOYMENT_DOMAIN
Merge pull request #3973 from seanmonstar/convict-0.4.0

update convict from 0.0.6 to 0.4.0

tests pass, front end, back end and Selenium. Thanks for working with me @seanmonstar, the updates make configuration significantly more understandable. r+
Merge pull request #3984 from jrgm/de-zerigofy-scripts-deploy

remove obsolete reference to env.ZERIGO_DNS_KEY and env.PERSONA_DEPLOY_DNS_KEY 

Nice cleanup @jrgm. Ephemeral deployments work every bit as well as before this PR. r+
Merge pull request #3969 from shane-tomlinson/issue-1704-address-info-statsd

Add statsd metric for looking up /.well-known/browserid
new and shiny

update all the things!