Fix usericons (#1408)

* Fix and refactor user icons, add Basic tests
* Remove identicon_canvas, use identicon.js
* Use octicon by default

test/test_history_view.rb

@@ -7,19 +7,5 @@ context "Precious::Views::History" do
     @history = Precious::Views::History.new
   end
 
-  test "string_to_code" do
-    # Result must match the following Java code.
-=begin
-	    public static void main(String[] args) throws Exception {
-		    final String s = "code@example.com";
-		    final byte[] b = MessageDigest.getInstance("SHA1").digest(s.toString().getBytes("UTF-8"));
-		    final int c = ((b[0] & 0xFF) << 24) | ((b[1] & 0xFF) << 16)
-				    | ((b[2] & 0xFF) << 8) | (b[3] & 0xFF);
-		    // 143327882
-		    System.out.println(c);
-	    }
-=end
-    actual = @history.string_to_code 'code@example.com'
-    assert_equal 143327882, actual
-  end
+  # No tests yet
 end