userportal,webadmin: Make resize easier

- Made resizing columns in the grid easier by making the resize
  area on both sides of the line.

Change-Id: I24259a9aa5c68a25a9ae8b3d0d1553190bec3441
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1037477
Signed-off-by: Alexander Wels <awels@redhat.com>