Add encrypted mailgun credentials

.gitattributes

@@ -1 +1,2 @@
 * text=auto
+**/mailgun.json filter=crypt diff=crypt

app/components/Preview.js

@@ -22,6 +22,7 @@ import { Component, PropTypes } from 'react';
 import { transform } from 'react-tools';
 import jsx from 'markdown-it-jsx';
 
+const mailgunUser = require( './../constants/mailgun.json' );
 
 // E-LEARNING MODULE COMPONENTS //
 
@@ -77,10 +78,7 @@ export default class Preview extends Component {
 
 			const transporter = nodemailer.createTransport({
 				'service': 'Mailgun',
-				'auth': {
-					'user': '',
-					'pass': ''
-				}
+				'auth': mailgunUser
 			});
 			global.sendMail = ( opts, clbk ) => {
 				transporter.sendMail( opts, clbk );

app/constants/mailgun.json

@@ -0,0 +1,3 @@
+U2FsdGVkX1++um8W1mUikFkCJ3UZegHGSZ259okoghAlIiDdf1GMkWoci0X8bNjx
+UBf3AZN6T5RcTjan0UqVt3c2c/a1ItZ7KOJu4fftazzzKiKD1Lzd86ZFMM96VBxY
+ot/7xEqE99TP3lvytB/GD6LywLfDXxtgUDXJwhz+JbU=