Add missing \ to string (#541)

    <string name="cal_pick_ics">Pick file to import</string>

    <!-- Strings to describe view details array -->

    <string name="show_time_no">Don't show time</string>

    <string name="show_time_no">Don\'t show time</string>

    <string name="show_time_start">Only start time</string>

    <string name="show_time_start_end">Start and end time</string>

    <string name="show_time_start_end_below">Start and end time below the event</string>