I want to addEnvironment(name, value) via code instead of xml file

[//]: # (
. Note: for support questions, please use Stackoverflow or Gitter**.
. This repository's issues are reserved for feature requests and bug reports.
.
. In case of any problems with Allure Jenkins plugin** please use the following repository
. to create an issue: https://github.com/jenkinsci/allure-plugin/issues
.
. Make sure you have a clear name for your issue. The name should start with a capital
. letter and no dot is required in the end of the sentence. An example of good issue names:
.
. - The report is broken in IE11
. - Add an ability to disable default plugins
. - Support emoji in test descriptions
)

#### I'm submitting a ...
- [ ] bug report
- [x] feature request
- [ ] support request => Please do not submit support request here, see note at the top of this template.

#### What is the current behavior?
I can't found add environment function in allure

#### If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem

#### What is the expected behavior?
I want to addEnvironment(name, value) via code

#### What is the motivation / use case for changing the behavior?
I want to add environment to show my test line info, and I use jenkins to executor our testcase

#### Please tell us about your environment:

- Allure version: 2.5.0
- Test framework: pytest@3.6.3
- Allure adaptor: allure-pytest@2.5.0

#### Other information

[//]: # (
. e.g. detailed explanation, stacktraces, related issues, suggestions
. how to fix, links for us to have more context, eg. Stackoverflow, Gitter etc
)

まず、allure-pytest アダプターにおける環境 XML の処理と公開 API を探します。この issue ではファイルやテストが指定されていません。コードベースの環境エントリをどこに置くべきかを判断し、アダプターを通じて name/value ペアを追加し、生成された Allure レポートで検証できることを完了条件とします。

索引モデルが issue の本文から書いたものです。