ChatView: allow loading css style sheets

Change the webview creation process so that we can load style sheets
from resources. In the future, we can load large CSS libraries without
having to include them in the HTML file.

Tuleap: #1073
Change-Id: Ie3a8cfd53b120c9f61a2dd3c33abb620817726c6
diff --git a/web/web.gresource.xml b/web/web.gresource.xml
index 33ab294..8749de3 100644
--- a/web/web.gresource.xml
+++ b/web/web.gresource.xml
@@ -10,5 +10,8 @@
       <file>linkify-string.js</file>
       <file>linkify-html.js</file>
       <file>linkify-jquery.js</file>
+
+      <!-- CSS -->
+      <file>chatview.css</file>
     </gresource>
   </gresources>