fix(Grid): fix Row gutter, default to 8px instead of 16px (#49)

Author: gregberge

packages/shared/core/Row.js

@@ -28,9 +28,6 @@ const Row = createComponent(() => ({
     children: PropTypes.node,
     gutter: PropTypes.oneOfType([PropTypes.number, PropTypes.string]),
   },
-  defaultProps: {
-    gutter: 15,
-  },
 }))
 
 export default Row

packages/shared/core/theme.js

@@ -209,7 +209,7 @@ export const controlFocusBoxShadow = p => color =>
 // Grid
 
 export const gridColumns = 12
-export const gridGutter = 16
+export const gridGutter = 8
 
 export const gridMaxWidths = {
   sm: '540px',