[omemo] Polish GUI

- Port Fingerprint dialog from openpgp plugin
- Add an InfoBar for errors and informations
- Add tooltip for device clearing
- Remove fingerprints tab from plugin config dialog

omemo/download_progress_dialog.ui

@@ -1,21 +1,25 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.20.0 -->
+<!-- Generated with glade 3.22.1 -->
 <interface>
-  <requires lib="gtk+" version="3.0"/>
+  <requires lib="gtk+" version="3.20"/>
   <object class="GtkDialog" id="progress_dialog">
     <property name="can_focus">True</property>
+    <property name="border_width">18</property>
     <property name="title" translatable="yes">Download</property>
     <property name="resizable">False</property>
     <property name="window_position">center-on-parent</property>
     <property name="destroy_with_parent">True</property>
     <property name="icon_name">go-down</property>
     <property name="type_hint">dialog</property>
+    <child>
+      <placeholder/>
+    </child>
     <child internal-child="vbox">
       <object class="GtkBox" id="dialog-vbox">
         <property name="width_request">250</property>
         <property name="visible">True</property>
         <property name="can_focus">False</property>
-        <property name="spacing">6</property>
+        <property name="spacing">12</property>
         <child internal-child="action_area">
           <object class="GtkButtonBox" id="dialog-action_area11">
             <property name="visible">True</property>
@@ -55,6 +59,20 @@
             <property name="position">0</property>
           </packing>
         </child>
+        <child>
+          <object class="GtkImage">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="tooltip_text">OMEMO</property>
+            <property name="margin_right">6</property>
+            <property name="pixbuf">omemo.png</property>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="position">0</property>
+          </packing>
+        </child>
         <child>
           <object class="GtkAlignment" id="alignment1">
             <property name="visible">True</property>