multi-part uploads, encryption, and setup.py

Hi @basak,

We've been using a fork of your glacier-cli tool and added three features.  If you are still maintaining this, we'd love to contribute them back and just be on the official release:
- a multipart_upload option for large files, with automatic retry for individual parts
- ```--encrypt``` and ```--decrypt``` options, leaning on ```gnugpg```
- a setup.py for installation management

Other cosmetic changes are to make it through PEP8 checks.

Best,
Scott