upgrades: Relabel from 'Update' to 'Software Update'

- The term 'Update' without a context is not easy to understand. This is
especially true during first setup wizard.

- This makes our UI similar to Android and lot of other OSes.

Tests:

- Trigger a update notification by incrementing FreedomBox version. In there,
the name of the app in the first line shows 'Software Update'.

- During first setup wizard, the title of the wizard step is 'Software Update'
initially and also when upgrades are running.

- In the System page, the title on the card is 'Software Update'. So is the
title on the app page.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/upgrades/__init__.py

@@ -71,7 +71,7 @@ class UpgradesApp(app_module.App):
         super().__init__()
 
         info = app_module.Info(app_id=self.app_id, version=self._version,
-                               is_essential=True, name=_('Update'),
+                               is_essential=True, name=_('Software Update'),
                                icon='fa-refresh', description=_description,
                                manual_page='Upgrades')
         self.add(info)
@@ -126,7 +126,7 @@ class UpgradesApp(app_module.App):
 
         data = {
             'version': plinth.__version__,
-            'app_name': 'translate:' + gettext_noop('Updates'),
+            'app_name': 'translate:' + gettext_noop('Software Update'),
             'app_icon': 'fa-refresh'
         }
         title = gettext_noop('FreedomBox Updated')

plinth/modules/upgrades/templates/update-firstboot-progress.html

@@ -8,7 +8,7 @@
 {% load static %}
 
 {% block content %}
-  <h2>{% trans "Update" %}</h2>
+  <h2>{% trans "Software Update" %}</h2>
 
   {% if is_busy %}
     <div class="upgrades-status-frame clearfix">

plinth/modules/upgrades/templates/update-firstboot.html

@@ -8,7 +8,7 @@
 {% load static %}
 
 {% block content %}
-  <h2>{% trans "Update" %}</h2>
+  <h2>{% trans "Software Update" %}</h2>
 
   <p>
     {% blocktrans trimmed %}

plinth/modules/upgrades/templates/upgrades-new-release.html

@@ -6,7 +6,7 @@
 {% load static %}
 
 <div class="notification-title">
-  {% blocktrans %}{{box_name}} Updated{% endblocktrans %}
+  {% blocktrans %}{{box_name}} updated{% endblocktrans %}
 </div>
 
 <p>