Unicorn timeouts configurable via `WEB_TIMEOUT`, still defaults to 30

The app always timed out when running on production mode locally
Prevent cached responses for users with an active `heroku_session` and sync sessions for non-JSON requests
Force reload after successful login by adding a timestamped param

Despite of #cd9dddb the redirection after logging in gets cached, further requests don't.
Add instructions to replicate the `heroku_session` behavior locally
Now that we included instructions to sync with heroku.com sessions locally, use them on development mode too