BURs: remove ability to skip secondary validations.

Remove the ability to skip secondary validations when creating a BUR.
The only skippable validation that still existed was the requirement
that both tags in an implication must have wiki pages. It's now
mandatory to write wiki pages for tags before you can request an
implication. This doesn't apply to empty tags.

test/unit/bulk_update_request_test.rb

@@ -309,6 +309,24 @@ class BulkUpdateRequestTest < ActiveSupport::TestCase
           assert_equal(true, @bur.valid?)
         end
       end
+
+      context "requesting an implication for an empty tag without a wiki" do
+        should "succeed" do
+          @bur = create(:bulk_update_request, script: "imply a -> b")
+          assert_equal(true, @bur.valid?)
+        end
+      end
+
+      context "requesting an implication for a populated tag without a wiki" do
+        should "fail" do
+          create(:tag, name: "a", post_count: 1)
+          create(:tag, name: "b", post_count: 1)
+          @bur = build(:bulk_update_request, script: "imply a -> b")
+
+          assert_equal(false, @bur.valid?)
+          assert_equal(["'a' must have a wiki page; 'b' must have a wiki page"], @bur.errors.full_messages)
+        end
+      end
     end
 
     context "when the script is updated" do