webadmin: enable gzip compression

- Enabled gzip compression for text mime types in
jboss configuration.

Change-Id: I7c0c5f88c1f58fc98775734f075bfa0bc867f8fc
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=889898
Signed-off-by: Alexander Wels <awels@redhat.com>