[#67] added export calendar functionnality (#294)

Co-authored-by: Camille Moussu <cmoussu@linagora.com>

src/locales/en.json

@@ -7,6 +7,8 @@
     "caldav_access": "CalDAV access",
     "secretUrl": "Secret URL",
     "secretUrlDesc": "The secret address can be used to view all calendar events even without access permissions. You can reset your current secret address and get a new one.",
+    "exportCalendar": "Export calendar",
+    "exportDesc": "Export your calendar to iCalendar format file (.ics) which you can import to other applications.",
     "import_file_description": "Import events from an ICS file to one of your calendars.",
     "ics_feed_url": "ICS feed URL",
     "import_to": "Import to",
@@ -31,7 +33,9 @@
     "create": "Create",
     "import": "Import",
     "add": "Add",
-    "reset": "Reset"
+    "reset": "Reset",
+    "export": "Export",
+    "exporting": "Exporting..."
   },
   "common": {
     "cancel": "Cancel",