Added basic wheels support

Following the basic guidelines on [pythonwheels.com](http://pythonwheels.com/) I've incorporated basic wheels support, so running:

```bash
make release
```

or
```bash
make sdist
```

Will compile the package in the new wheels format alongside the standard older format.

However, a pip install is required first, so I've added wheels==0.22.0 into the requirements.txt file to support this:

```bash
pip install -r requirements.txt
```