Ability for completion/going-to-definition for symbols from virtualenv bound to specific project

I use [pyenv](https://github.com/pyenv/pyenv) to keep multiple python installation (py2, py3 etc.)

And I use [pyenv-virtualenv](https://github.com/pyenv/pyenv-virtualenv) to maintain separate python environments for different projects (i.e. virtualenv).

All python versions and virtualenvs live in directory `~/.pyenv/versions`.

```shell
$ ls ~/.pyenv/versions
2.7.13 2.7.14 3.6.3 3.6.4 3.7.0 project-x project-y

$ ~/.pyenv/versions/3.7.0/bin/python -V
Python 3.7.0

$ ~/.pyenv/versions/project-x/bin/python -V
Python 2.7.14
```

All my projects' code live in `~/workspace`:

```shell
$ ls ~/workspace
project-x project-y
```

I always make my project name as the same as its virtualenv name, you see, there are `project-x` and `project-y`.

I also place a file named of `.python-version` under project root dir, [let the magic automatically activate the specific virtualenv on entering project dir](https://github.com/pyenv/pyenv-virtualenv#activate-virtualenv).

```shell
$ cat ~/workspace/project-x/.python-version
project-x

$ cd ~/workspace/project-x
(project-x) $
```

I use [Atome Project Manager](https://atom.io/packages/project-manager) to remember my project dirs, So I can do quick switch from and to different editor windows, each window for one project.

---

So I want **IDE-python** call the right python binary and do completion/going-to-definition from the right python environment, Possible?

首先跟踪 IDE-python 如何为 Atom 项目选择解释器，并使用项目根目录中的 .python-version 和 pyenv 路径作为复现设置。当 completion 和 go-to-definition 针对 project-x 和 project-y 从所选项目的 virtualenv 中解析符号，而不是从共享的 Python 安装中解析时，即表示完成。

由索引模型根据 Issue 内容生成。