Add `tag(attr: false)` syntax. Thanks, Hunter!

http://git.debu.gs/gitweb/?p=hoshi;a=commitdiff;h=56a9321ef7c4732b64de285c1608dd5a36df3fc5
code, git.debu.gs | 2017-06-27 20:29:19 +0000 GMT | No.705

Add `tag(attr: false)` syntax.  Thanks, Hunter!

[D H] Rakefile
[D H] lib/hoshi/monkey_patches.rb
[D H] test/tag_test.rb