Implemented refresh option in regatta activity

Implemented another observer pattern in RegattaFragment and
RegattaActivity.
Added option item in RegattaActivity. Added new strings for refresh
option.

mobile/com.sap.sailing.android.tracking.app/res/menu/options_menu_with_checkout.xml

@@ -18,4 +18,9 @@
         android:id="@+id/options_menu_add_team_image"
         android:title="@string/options_add_team_photo"
         app:showAsAction=""/>
+
+    <item
+        android:id="@+id/options_menu_refresh"
+        android:title="@string/options_refresh"
+        app:showAsAction=""/>
 </menu>

mobile/com.sap.sailing.android.tracking.app/res/values-de/strings.xml

@@ -9,6 +9,7 @@
     <string name="options_menu_checkout">Checkout</string>
     <string name="options_add_team_photo">Team Foto hinzufügen</string>
     <string name="options_replace_team_photo">Team Foto ersetzen</string>
+    <string name="options_refresh">Aktualisieren</string>
     <string name="settings_category_other">Andere Einstellungen</string>
     <string name="scan_hint">Der QR-Code befindet sich auf Ihrer Teilnahmebestätigung</string>
     <string name="device_identifier">Geräte-ID</string>

mobile/com.sap.sailing.android.tracking.app/res/values/strings.xml

@@ -7,6 +7,7 @@
     <string name="options_menu_checkout">Checkout</string>
     <string name="options_add_team_photo">Add Team Photo</string>
     <string name="options_replace_team_photo">Replace Team Photo</string>
+    <string name="options_refresh">Refresh</string>
     <string name="settings_category_other">Other Settings</string>
     <string name="device_identifier">Device Identifier</string>
     <string name="tracker_started">SAP Sailing Tracker started</string>