Replace freenode webchat with Scrollback, closes #65

Changes made to the original PR #65:
- Edit the URL in `source`, not in the generated `public` directory.
- Use the more common IRC look with the 'all-messages' view

source/templates/main.html

@@ -53,7 +53,7 @@
       {{link 'pages.releases'}}<!--
    --><a href="https://github.com/iojs/io.js/issues">{{i18n.issues-link}}</a><!--
    --><a href="https://github.com/iojs">{{i18n.org-link}}</a><!--
-   --><a href="https://webchat.freenode.net/?channels=io.js">{{i18n.irc-link}}</a><!--
+   --><a href="https://scrollback.io/iojs/all/all-messages">{{i18n.irc-link}}</a><!--
    --><a href="http://logs.libuv.org/io.js/latest">{{i18n.irc-logs-link}}</a><!--
    --><a href="https://github.com/iojs/io.js/blob/v1.x/GOVERNANCE.md#readme">{{i18n.gov-link}}</a>
     </nav>