hosted_engine_page: Improve user interface

This patch improves the user interface:
 - Better description in the label
 - Shows errors/messages directly in the TUI instead of shell console
 - Handled exception

Change-Id: I1f2b7e1857231cf2002175bbe9fc03e650e79ac6
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>