Lint Slim files and fix offenses

The fixing was partially done manually and partially automatically.

app/views/statistics/activity_history.html.slim

@@ -12,14 +12,14 @@
   .graph id="#{resource}-activity-history"
   form
     .mb-3
-      label for="from-date" = t('.from')
-      input type="date" class="form-control" id="from-date" name="from" value=(params[:from] || DateTime.new(2016).to_date)
+      label for='from-date' = t('.from')
+      input.form-control#from-date type='date' name='from' value=params[:from] || DateTime.new(2016).to_date
     .mb-3
-      label for="to-date" = t('.to')
-      input type="date" class="form-control" id="to-date" name="to" value=(params[:to] || DateTime.now.to_date)
+      label for='to-date' = t('.to')
+      input.form-control#to-date type='date' name='to' value=params[:to] || DateTime.now.to_date
     .mb-3
-      label for="interval" = t('.interval')
-      select class="form-control" id="interval" name="interval"
-        = [:year, :quarter, :month, :day, :hour, :minute, :second].each do | key |
+      label for='interval' = t('.interval')
+      select.form-control#interval name='interval'
+        = %i[year quarter month day hour minute second].each do |key|
           option selected=(key.to_s == params[:interval]) = key
-    button type="submit" class="btn btn-primary" = t('.update')
+    button.btn.btn-primary type='submit' = t('.update')

app/views/statistics/show.html.slim

@@ -1,9 +1,8 @@
-
 #statistics-container
-  - statistics_data.each do | section |
+  - statistics_data.each do |section|
     h2 = section[:name]
     .statistics-wrapper data-key=section[:key]
-      - section[:entries].each do | entry |
+      - section[:entries].each do |entry|
         a href=entry[:url]
           div data-key=entry[:key]
             .title = entry[:name]