Update installer UI for easier region selection

[allen]

From Tony Arnold:

The time zone field should be broken down into separate select boxes - country, then region. Having to scroll through hundreds of entries is bad form.

[allen]

From Alistair:

Requires some logic in the Installer code. Currently using the timezone list exposed by PHP system call. Not all that important. Would take me an hour.

Oh, I should add, the installer should be doing a best-guess with regards to timezone/country. I think currently that is not the case. Really only need to use the system default timezone. Could potentially use a 3rd party service to lookup based on client IP.