Update Swift template for Swift 3

[brockboland]

I'm not sure if anything needs to change, but if it does, perhaps we should include an option to specify which version of Swift should be generated.

[designatednerd]

Good idea. IIRC there's some kind of xcode 8 autocomplete stuff that became available too but I haven't watched the sessions yet. 😝

[brockboland]

It auto-completes the names of images, but if said images disappear/are renamed/whatever, it's a runtime error. Cat2Cat (or R.swift) is still worth using to ensure those mistakes are caught at build time.

[designatednerd]

Oh blah, that's annoying. Yah, we should update.