webadmin: Overlapped in 'New Virtual Machine - Guide Me' dialog

In fr_FR locale the text did not fit into buttons in new VM guide me dialog.

Fixed by changing the styles in a way that when the text is longer than 250px
(min width) than the button grows.

Change-Id: Icde29a47a3c78f73cca9eaaf0db875c5b82ea0e8
Bug-Url: https://bugzilla.redhat.com/1123762
Signed-off-by: Tomas Jelinek <tjelinek@redhat.com>