Remove string attribute from views

issue2350

view/action_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="Dashboard Action">
+<form>
     <label name="user"/>
     <field name="user"/>
     <newline/>

view/action_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="Dashboard Actions">
+<tree>
     <field name="user"/>
     <field name="sequence"/>
     <field name="act_window"/>

view/action_tree_sequence.xml

@@ -1,6 +1,6 @@
 <?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="Dashboard Actions" sequence="sequence">
+<tree sequence="sequence">
     <field name="act_window" expand="1"/>
 </tree>

view/dashboard.xml

@@ -1,5 +1,5 @@
 <?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. -->
-<board string="Dashboard">
+<board>
 </board>