rely on setuptools for console scripts and shebangs

Given a system where `/usr/bin/python` is Python 3, and `/usr/bin/python2` is Python 2, if you install supernova with `python2 setup.py install`, the shebangs in the code cause it to still invoke Python 3.  When using setuptools, the correct shebang is added to the console scripts automatically.  For example, after running the install command above, `/usr/bin/supernova` has the following content.

```
#!/usr/bin/python2
# EASY-INSTALL-ENTRY-SCRIPT: 'supernova==1.0.7','console_scripts','supernova'
__requires__ = 'supernova==1.0.7'
import sys
from pkg_resources import load_entry_point

if __name__ == '__main__':
    sys.exit(
        load_entry_point('supernova==1.0.7', 'console_scripts', 'supernova')()
    )
```

Therefore, the shebangs in supernova's code are unnecessary and problematic.  The scripts under `bin/` also appear to be obsolete.