fix - partial fix for styleguidist#879

- improves accessibility in the example application for various components
- to meet WCAG 2.0 color contrast requirements foreground/background must have a ratio of 4.5.1 or greater
- side-bar navigation links, darkened link color #1978c8 -> #1873bf
- PropType table, darkened prop ```name``` color #7f9a44 -> #667c36
- PropType table, darkened ```type``` color #b77daa -> #a15994
- VersionRenderer - changed the text color from ```color.light``` -> ```color.error```

Author: Jeremy Levy

Diff for: src/rsg-components/Version/VersionRenderer.js

@@ -4,7 +4,7 @@ import Styled from 'rsg-components/Styled';
 
 const styles = ({ color, fontFamily, fontSize }) => ({
 	version: {
-		color: color.light,
+		color: color.error,
 		margin: [[5, 0, 0, 0]],
 		fontFamily: fontFamily.base,
 		fontSize: fontSize.base,

Diff for: src/styles/theme.js

@@ -13,11 +13,11 @@ export const color = {
 	base: '#333',
 	light: '#767676',
 	lightest: '#ccc',
-	link: '#1978c8',
+	link: '#1873bf',
 	linkHover: '#f28a25',
 	border: '#e8e8e8',
-	name: '#7f9a44',
-	type: '#b77daa',
+	name: '#667c36',
+	type: '#a15994',
 	error: '#c00',
 	baseBackground: '#fff',
 	codeBackground: '#f5f5f5',