feat(client/deis): add python3 support

Changes:
- use python future for single source
- change octals to new style of `0oXXX`
- add `future==0.14.1` as dependency

Breaking Changes:
- `future==0.14.1` requires python >= 2.6
Maybe this should be a conditional import such as:

```python
try:
    from http.cookiejar import MozillaCookieJar
except Exception as err
    from cookielib import MozillaCookieJar
```