Move `theme` to glamorous props

[atticoos]

This is a parity story to https://github.com/paypal/glamorous/issues/219.

Before

const MyText = glamorous.text((props, theme) => ({
  fontSize: theme.main.fontSize,
}))

After

const MyText = glamorous.text(({theme}) => ({
  fontSize: theme.main.fontSize,
}))

[kwelch]

Should be closable 🎉