AccountCreationWizard: ensure buttons have same size

This ensures that buttons in the first window of the
AccountCreationWizard have the same size. The "Link device to an
existing account" button used to be larger and it seemed out of place.

Change-Id: I0b27c528f293e38e91dc471a795ae411434cd71a
Reviewed-by: Stepan Salenikovich <stepan.salenikovic@savoirfairelinux.com>
diff --git a/ui/accountcreationwizard.ui b/ui/accountcreationwizard.ui
index 57d0b28..ebf94e1 100644
--- a/ui/accountcreationwizard.ui
+++ b/ui/accountcreationwizard.ui
@@ -61,6 +61,7 @@
                     <property name="visible">True</property>
                     <property name="orientation">vertical</property>
                     <property name="spacing">15</property>
+                    <property name="homogeneous">True</property>
                     <child>
                       <object class="GtkButton" id="button_existing_account">
                         <property name="label" translatable="yes">Link this device to an existing account</property>