webadmin: Events tab message column too narrow

The message column in events tab is too narrow in
basic view. There is lots of space unused and the
message column should use available space in
basic view.

Change-Id: I10cfae5d4fec96a091981b3768648b3a908aa41a
Bug-Url: https://bugzilla.redhat.com/1149491
Signed-off-by: Ravi Nori <rnori@redhat.com>