Revert "想定しない脆弱性を防ぐため default modifier に HTMLPurifier を適用する"

[nanasess]

Reverts #1066

HTMLPurifier で、シングルクォーテーションやダブルクォーテーションがデコードされて出力されてしまう。
これだと hidden 項目などに使えないため差し戻しする

http://htmlpurifier.org/demo.php?filter%5BAutoFormat.AutoParagraph%5D=0&filter%5BAutoFormat.DisplayLinkURI%5D=0&filter%5BAutoFormat.Linkify%5D=0&filter%5BAutoFormat.RemoveEmpty.Predicate%5D=colgroup%3A%0D%0Ath%3A%0D%0Atd%3A%0D%0Aiframe%3Asrc%0D%0A&filter%5BAutoFormat.RemoveEmpty%5D=0&filter%5BAutoFormat.RemoveSpansWithoutAttributes%5D=0&filter%5BNull_CSS.AllowedProperties%5D=1&filter%5BCore.CollectErrors%5D=0&filter%5BNull_HTML.Allowed%5D=1&filter%5BNull_HTML.Doctype%5D=1&filter%5BHTML.SafeObject%5D=0&filter%5BHTML.TidyLevel%5D=medium&filter%5BURI.DisableExternalResources%5D=0&filter%5BNull_URI.Munge%5D=1&html=%26quot%3Baaa%26quot%3B%0D%0A%26%23039%3Bbbb%26%23039%3B&submit=Submit

以下を HTMLPurifier に通すと、

"aaa"
'bbb'

以下のように出力されてしまう

"aaa"
'bbb'

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 50.61%. Comparing base (23e9e54) to head (7aebe82).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1098      +/-   ##
==========================================
- Coverage   50.94%   50.61%   -0.34%     
==========================================
  Files          80       80              
  Lines       10256    10256              
==========================================
- Hits         5225     5191      -34     
- Misses       5031     5065      +34     

Flag	Coverage Δ
tests	50.61% <ø> (-0.34%)	⬇️

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