UI for AWS SDK for PHP module

Did a bit of cleanup:
- removed trailing spaces
- don't think there is a hook_admin() so I used _form() which seems to be standard
- updated form function signature
- moved to just ui/awssdk_ui.* we can always move if we add more modules since git makes that easy

Something we should probably decide since I suppose it would require an update hook to be correct is the variable namespace. It was something I considered originally, but the amazon variables already have 'aws' at the front which seemed sufficient. I removed it from the patch, but I can see it either way.

Something else to consider, do we want any of the fields to be password fields as they are all technically private keys. I think mollom module for example doesn't hide keys.

Lastly, just a cool thought we could make it auto generate settings page since the module already pulls all the defined constants, get the comments shouldn't be much harder. Could switch it over to use PHP's token_get_all() that way it automatically updates with the SDK. Not sure if we want to go that far.

I am happy to commit this patch, we can always add the namespace or automatic later. I should then probably add a UI component for issues.

Committed, thanks.