adds a button to copy the generated config to the buffer as base64 string (#85)

* add copy base64 zip string for paste in console like
$ echo 'base64string' | base64 --decode > nginxconfig.io.zip

* preparing for merge

* copyAsBase64()

* added copy-paste steps

.eslintrc

@@ -42,6 +42,8 @@
 		"hljs": true,
 		"JSZip": true,
 		"Masonry": true,
-		"saveAs": true
+		"saveAs": true,
+		"Base64": true,
+		"FileReader": true
 	}
 }