Perspective.py

I forgot the fact that in Python, dots are used for importing packages from child directories hence package names cannot include dots. Therefore I've updated the code to make the package name `perspective` yet keep the PyPI name as `perspective.py`.

Now you can import perspective.py as follows:
python
from perspective import Client, Attributes

Furthermore, you can still install the package by the following command:
powershell
python -m pip install --upgrade perspective.py

This is the initial release of perspective.py library. The code is pretty simple thereby I don't think there are lots of bugs; but if you find any or if you have any suggestions, feel free to create an issue in Issues tab or make a pull request. Current features in this version follow as:

- Making an analysis request to the Perspective API with requested attributes and specified language.
- Being able to correct spelling mistakes in attribute names and languages in `analyze` command arguments.

I will upload the library to PyPI soon.