Add default .slate configuration

Via https://github.com/jigish/slate/blob/ff5ee5a/Slate/default.slate
Add binding to reload .slate file
Port my SizeUp config to Slate

Port my preferred SizeUp window proportions and keybindings to Slate.
Configure Slate window hints
Use screenOriginX/screenOriginY instead of 0

From the Slate wiki:

> Remember to offset with `screenOriginX` in your `topLeftX` and
> `screenOriginY` in your `topLeftY` when using the `screen` option
> (or when using multiple screens in general) or your move operation
> will offset from the default origin `(0,0)` which is the origin of
> screen `0`.
Add binding to unto last Slate op
Add resize bindings for Slate