You need all these MIME types. Most of them are probably inherited from higher up but I needed to add a couple - could have been a version thing!
.manifest
application/manifest
.xaml
application/xaml+xml
.dll
application/x-msdownload
.application
application/x-ms-application
.xbap
application/x-ms-xbap
.deploy
application/octet-stream
.xps
application/vnd.ms-xpsdocument
.xap
application/x-silverlight-app
I found this StackOverflow question useful