[brew doctor] remove check_for_pydistutils_cfg_in_home

This check is essentially noise since the [associated issue](http://bugs.python.org/issue6138) is closed. Further, I don't think the `check_for_pydistutils_cfg_in_home` was correctly depicting the bug as reported anyhow. The real issue as noted by the OP of the issue was that he had put `home` in that file which was causing the issue.

The `check_for_pydistutils_cfg_in_home` method is not adequate. It actually just checks that the file `~/.pydistutils.cfg` exists. This was not the issue.

Further, I have a `~/.pydistutils.cfg` file and the contents are the following:

```
[install]
prefix=
```

I was only able to install `powerline` after having this set. I'm sure there are a ton of different variations out there. This being the case, perhaps `brew` cannot or should not attempt to get into such things since there are too many variables in play.