Features/pip

- Adds bindings for all methods. Closes #23. Closes #24. Closes #3.
- Ability to install using pip. Closes #35.
- Ability to install into casapy. Closes #36.

On most platforms, it is possible to run the python tests with:

```Python
import nose
nose.runmodule('purify')
```

On others, one can do:
```
import purity.tests
import nose
from os.path import dirname
nose.main(dirname(purify.tests))
```