Update Swift code for Xcode 6 beta 5

Mostly mundane tweaks for changes to Swift. The two big ones are that swift's
name mangling is now just "module.classname" and that all properties have to be
explicitly declared as `dynamic`.

Closes #733.
Well, that sort of covers why just using `className` to get the module name doesn't always work. For writing migration code you'd either need to use `#if` or get the module name from another class if the migration code is used for multiple targets. It'd also make sharing realm files between multiple things much more awkward.