Quote all config values for consistency

Without this we are relying on implicit string conversion for no benefit.

Author: adamwathan

stubs/defaultConfig.stub.js

@@ -191,23 +191,23 @@ module.exports = {
       '6xl': '4rem',
     },
     fontWeight: {
-      hairline: 100,
-      thin: 200,
-      light: 300,
-      normal: 400,
-      medium: 500,
-      semibold: 600,
-      bold: 700,
-      extrabold: 800,
-      black: 900,
+      hairline: '100',
+      thin: '200',
+      light: '300',
+      normal: '400',
+      medium: '500',
+      semibold: '600',
+      bold: '700',
+      extrabold: '800',
+      black: '900',
     },
     lineHeight: {
-      none: 1,
-      tight: 1.25,
-      snug: 1.375,
-      normal: 1.5,
-      relaxed: 1.625,
-      loose: 2,
+      none: '1',
+      tight: '1.25',
+      snug: '1.375',
+      normal: '1.5',
+      relaxed: '1.625',
+      loose: '2',
     },
     letterSpacing: {
       tighter: '-0.05em',
@@ -355,12 +355,12 @@ module.exports = {
     },
     zIndex: {
       auto: 'auto',
-      '0': 0,
-      '10': 10,
-      '20': 20,
-      '30': 30,
-      '40': 40,
-      '50': 50,
+      '0': '0',
+      '10': '10',
+      '20': '20',
+      '30': '30',
+      '40': '40',
+      '50': '50',
     },
     opacity: {
       '0': '0',
@@ -382,12 +382,12 @@ module.exports = {
       none: 'none',
     },
     flexGrow: {
-      '0': 0,
-      default: 1,
+      '0': '0',
+      default: '1',
     },
     flexShrink: {
-      '0': 0,
-      default: 1,
+      '0': '0',
+      default: '1',
     },
     order: {
       first: '-1',
@@ -412,7 +412,7 @@ module.exports = {
       decimal: 'decimal',
     },
     inset: {
-      '0': 0,
+      '0': '0',
       auto: 'auto',
     },
     container: {}