Don't try to count a relation with aliases

Work around ActiveRecord count and column aliases issue as described at:
  <https://github.com/rails/rails/issues/15138#issuecomment-61325080>

AR doesn't promise that `#count` (which is called by `#any?`) will work
for relations using `#select`, which means we need a workaround instead.

app/views/shared/_issues.html.haml

-- if @issues.any?
+- if @issues.reorder('').any?
   - @issues.group_by(&:project).each do |group|
     .panel.panel-default.panel-small
       - project = group[0]