export feature for tracks and booths are done

app/views/admin/tracks/_confirmed_tracks.xlsx.axlsx

@@ -0,0 +1,29 @@
+wb.add_worksheet(name: 'all tracks') do |sheet|
+  bold_style = wb.styles.add_style(b: true)
+  wrap_text = wb.styles.add_style alignment: {wrap_text: true}
+  row = ['Track ID',
+         'Name',
+         'Description',
+         'Room',
+         'Start Date',
+         'End Date',
+         'Submitter Name',
+         'Included in Cfp',
+         'State']
+  sheet.add_row row, style: bold_style
+
+  @tracks.confirmed.each do |track|
+    row = []
+    row << track.id
+    row << track.name.to_s
+    row << track.description.to_s
+    row << track.try(:room).try(:name)
+    row << track.start_date.to_s
+    row << track.end_date.to_s
+    row << track.try(:submitter).try(:name)
+    row << (track.cfp_active? ? 'Yes' : 'No')
+    row << track.state
+    sheet.add_row row , style: wrap_text
+    sheet.column_widths 10,20,50,20,12,12,20,15,10
+  end
+end