Proposed new timezone method for FormHelper

### Some background

Every implementation I've seen of a drop down list of timezones has been very poor in terms of UX. The select is easy to use, but the lists I've seen presented, although correct, are not often clear for your average user. 

For a developer it's easy to just offer a select input of UTC offsets or timezone identifiers, but to 95% of real World web users this is confusing, do people <b>really</b> know how many hours ahead or behind of UTC they are? Is it daylight saving or standard? 

At work, we have had a headache with users choosing the wrong timezone, and in our app these times are actually deadlines, so when a user does this wrong it's a real pain. 

So we created a helper. Basically, if offers a 2-tier select with the top level being the Country. Everyone knows what Country they are in (right? :smile: )

![screen shot 2013-05-17 at 15 29 03](https://f.cloud.github.com/assets/222958/518764/f47df39c-bf04-11e2-83f8-0446c2f83235.png)
![screen shot 2013-05-17 at 15 28 36](https://f.cloud.github.com/assets/222958/518772/09751bb8-bf05-11e2-9543-b0d9709e8ab6.png)

The second tier offers a list of the possible timeszones in that Country, along with the local time for each. This makes the choice for users much easier if they don't know what GMT or UTC is.

Could be a nice option for the FormHelper! Thoughts?