tumblr: convert commentary to dtext.

* Convert Tumblr commentary to DText.
* Strip extraneous whitespace in links and blockquotes.
* Add newlines after block elements to ensure they're separated from
  subsequent blocks.

test/unit/sources/deviantart_test.rb

@@ -35,14 +35,11 @@ module Sources
       should "get the dtext-ified commentary" do
         desc = <<-EOS.strip_heredoc.chomp
           blah blah
-          
           "test link":[http://www.google.com]
-          
-
 
           h1. lol
 
-          
+
 
           [b]blah[/b] [i]blah[/i] [u]blah[/u] [s]blah[/s]
           herp derp
@@ -53,7 +50,6 @@ module Sources
           * two
           * three
           
-          
           * one
           * two
           * three

test/unit/sources/tumblr_test.rb

@@ -42,6 +42,26 @@ module Sources
         assert_equal(desc, @site.artist_commentary_desc)
       end
 
+      should "get the dtext-ified commentary" do
+        desc = <<-EOS.strip_heredoc.chomp
+          h2. header
+
+          plain [b]bold[/b] [i]italics[/i] [s]strike[/s]
+
+          * one
+          * two
+
+          * one
+          * two
+
+          [quote]quote[/quote]
+
+          "link":[http://www.google.com]
+        EOS
+
+        assert_equal(desc, @site.dtext_artist_commentary_desc)
+      end
+
       should "get the image url" do
         assert_equal("http://data.tumblr.com/3bbfcbf075ddf969c996641b264086fd/tumblr_os2buiIOt51wsfqepo1_raw.png", @site.image_url)
       end