ui:renamed daemon version label for better clarity

The GUI and daemon versions are displayed in 2 different locations:
 - ui: in the title of the main window.
 - daemon: in the lower right corner.

Now instead of showing the daemon version as "Version: x.y.z", we
show "Daemon version: x.y.z".

Closes: #1278

Author: gustavo-iniguez-goya

ui/opensnitch/res/stats.ui

@@ -2275,7 +2275,7 @@
         </font>
        </property>
        <property name="text">
-        <string>Version</string>
+        <string>Daemon version</string>
        </property>
        <property name="alignment">
         <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignVCenter</set>