ISSUE-21: Index all pages (not just blog pages) (#27)

Previously we only included links that end with `.html` from the
different sitemaps. Now we include all pages.

The same conditions used to exclude some specifig pages from our index
has been left in place. We also exclude URLs with a hash param.
Reject condition: `x.match?(/#.+\z/) || x.include?('page') || x.include?('/tags/') || x.include?('author')`

We removed the where condition in the links_controller.
Now links without published_at will show.
This also means that links without  published_at will appear at the top
of the links page.
See: https://stackoverflow.com/a/44912964

See: #21

app/controllers/links_controller.rb

@@ -8,7 +8,7 @@ def index
     else
       Link
     end
-    @links = scope.where("published_at IS NOT NULL").order(published_at: "DESC")
+    @links = scope.order("published_at DESC NULLS LAST")
   end
 
   # GET /links/1

app/models/link.rb

@@ -8,7 +8,9 @@ class Link < ApplicationRecord
 
   class << self
     def find_urls(sitemap)
-      sitemap.to_a.select {|x| x.end_with? ".html" }.reject {|x| x.include?("page") || x.include?("/tags/") || x.include?("author") }
+      sitemap.to_a.reject do |x|
+        x.match?(/#.+\z/) || x.include?('page') || x.include?('/tags/') || x.include?('author')
+      end
     end
 
     def find_description(page)