Remove button "Cancel" from modal dialog

Only one of the modal dialogs in Kimchi has a "Cancel" button along with
the form submit button. That button layout is inconsistent with the rest of
the application and it provides the same functionality as the "X" button
present at the top of every dialog.

Remove the button "Cancel" from the dialog "Edit template".

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
Fix text alignment on storage pool type combo boxes

The storage pool type list does not have a left padding like the
other combo boxes in Kimchi, bringing the text very close to the UI
component's border.
The SCSI device list on the same window has the same alignment problem.

Apply a common CSS class to the combo boxes so they look like the other
objects in the application.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>