I have an installed Spark 1.1.3 client that times-out when I attempt to query the available plugins. Upon further investigation, I found that the client is attempting to contact the server 63-246-20-123.contegix.com on port 80. This is not our Spark server…
The plugins themselves exist on jivesoftware.org and not the wildfire server. You can try to use the http proxy settings in the advanced tab of the Spark Login screen to see if this helps.