Various bug fixes.

- App failing to exit after not being able to connect to persistency.
- Geocoder performing two callbacks instead of one (leading to crash)
where Bing API key incorrect and a bad status code is returned.
- Request processing for getting meeting list was not terminated even if
the email was found to be invalid, leading to a potential error.
- Improved error messages on UNIX platforms where admin privileges are
required to bind port needed for http server.