� Improve Button component stylesheet; removed duplicate styles (facebook#21535)

Summary:
Updated Button component inspiration. Refactored code takes advantage of Platform Specific Code, as we want to re-use as much code as possible.

1. Import Button component
2. Button should work the same

facebook#19752

[GENERAL] [ENHANCEMENT] [Button] - Uses spread operator for platform specific code in creating styles
Pull Request resolved: facebook#21535

Differential Revision: D10248048

Pulled By: TheSavior

fbshipit-source-id: 7260fa56f15b70b7c9499c8da418db7b2214b0dd

Author: cHaLkdusT

Libraries/Components/Button.js

@@ -150,21 +150,21 @@ const styles = StyleSheet.create({
       borderRadius: 2,
     },
   }),
-  text: Platform.select({
-    ios: {
-      // iOS blue from https://developer.apple.com/ios/human-interface-guidelines/visual-design/color/
-      color: '#007AFF',
-      textAlign: 'center',
-      padding: 8,
-      fontSize: 18,
-    },
-    android: {
-      color: 'white',
-      textAlign: 'center',
-      padding: 8,
-      fontWeight: '500',
-    },
-  }),
+  text: {
+    textAlign: 'center',
+    padding: 8,
+    ...Platform.select({
+      ios: {
+        // iOS blue from https://developer.apple.com/ios/human-interface-guidelines/visual-design/color/
+        color: '#007AFF',
+        fontSize: 18,
+      },
+      android: {
+        color: 'white',
+        fontWeight: '500',
+      },
+    }),
+  },
   buttonDisabled: Platform.select({
     ios: {},
     android: {