don't allow insert of links that's missing either title or URL

package.json

     "type": "git",
     "url": "https://github.com/wix-private/react-native-ZSSRichTextEditor.git"
   },
-  "version": "0.1.4",
+  "version": "0.1.5",
   "description": "React Native Wrapper for ZSSRichTextEditor",
   "main": "index.js",
   "license": "UNLICENSED",

src/RichTextEditor.js

   }
 
   _renderModalButtons() {
-    const insertDisabled = this.state.linkTitle.length <= 0;
+    const insertDisabled = this.state.linkTitle.trim().length <= 0 || this.state.linkUrl.trim().length <= 0;
     const containerPlatformStyle = PlatfomIOS ? {justifyContent: 'space-between'} : {paddingTop: 15};
     const buttonPlatformStyle = PlatfomIOS ? {flex: 1, height: 45, justifyContent: 'center'} : {};
     return (