Remove string attribute from views

issue2350

view/country_form.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<form string="Country">
+<form>
     <label name="name"/>
     <field name="name"/>
     <label name="code"/>

view/country_tree.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<tree string="Countries">
+<tree>
     <field name="name"/>
     <field name="code"/>
 </tree>

view/subdivision_form.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<form string="Subdivision">
+<form>
     <label name="country"/>
     <field name="country"/>
     <newline/>

view/subdivision_tree.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<tree string="Subdivisions">
+<tree>
     <field name="name"/>
     <field name="code"/>
     <field name="type"/>

view/zip_form.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<form string="Zip">
+<form>
     <label name="country"/>
     <field name="country"/>
     <label name="subdivision"/>

view/zip_list.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <!-- This file is part of Tryton.  The COPYRIGHT file at the top level of
 this repository contains the full copyright notices and license terms. -->
-<tree string="Zip">
+<tree>
     <field name="country"/>
     <field name="subdivision"/>
     <field name="zip"/>