Respect Template Options in Before Blocks

I ran into a bug while trying to use compass. When calling render in a before block (Stasis::Render#render) configuration set with `Stasis::Options.set_template_option` was ignored. This patch merges options passed at the end of a call to `render` inside a `before` block with `Stasis::Options.get_template_option` -- I was inspired by Stasis#render

Please see issue #31's [comments](https://github.com/winton/stasis/issues/31#issuecomment-12288883) for some history.

I wrote two specs, they feel a little gross, but I don't know how else to test this behavior.