v1.8.1 release

Bug fixes :

• Fix summernote integration problem. Thanks @pyaehein.
• Fix cannot see picture when not logged in.
• Fix problems with utf8 url. Thanks @khjay.

Feature :

• Add summernote to demo page.
• Click on image with open new preview window if editor integration is not found. Thanks @coryw.
• Integrated with StyleCI.
• Show a message when uploaded a file. Thanks @abdi42 .