tools: Domain name should be case insensitive

Domain name should be case insensitive. This patch by default converts
domain entered by user to lower case so it can be easily compared and
used as a key in maps.

Change-Id: I2573933e6ded5644f3c0c4c532e2407d753b9f4f
Bug-Url: https://bugzilla.redhat.com/1078147
Signed-off-by: Martin Perina <mperina@redhat.com>