Fix system.map handling

Zapp creation, bundling, and execution was pretty much broken, evidently due to d0325d7ac043a0a3ae62541ec78daccc9cce66ab.

Exceptions like this would get thrown:

```
~/proj/hello  $ ~/proj/zpm/zpm bundle && ~/proj/zpm/zpm deploy -l debug -V 2.0 foo hello.zapp --execute
created hello.zapp
INFO:zpmlib.commands: deploying hello.zapp
No handlers could be found for logger "keystoneclient.session"
INFO:zpmlib.zpm: Container 'foo' not found. Creating it...
Traceback (most recent call last):
  File "/Users/lars/proj/zpm/zpm", line 29, in <module>
    args.func(args)
  File "/Users/lars/proj/zpm/zpmlib/commands.py", line 94, in inner
    return func(namespace, *args, **kwargs)
  File "/Users/lars/proj/zpm/zpmlib/commands.py", line 236, in deploy
    zpm.deploy_project(args)
  File "/Users/lars/proj/zpm/zpmlib/zpm.py", line 521, in deploy_project
    deploy_index = _deploy_zapp(conn, args.target, args.zapp, auth_opts)
  File "/Users/lars/proj/zpm/zpmlib/zpm.py", line 448, in _deploy_zapp
    for path, data, content_type in uploads:
  File "/Users/lars/proj/zpm/zpmlib/zpm.py", line 465, in _generate_uploads
    job = _prepare_job(tar, zapp_config, swift_url)
  File "/Users/lars/proj/zpm/zpmlib/zpm.py", line 236, in _prepare_job
    fp = tar.extractfile('%s.json' % zapp['meta']['name'])
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/tarfile.py", line 2110, in extractfile
    tarinfo = self.getmember(member)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/tarfile.py", line 1794, in getmember
    raise KeyError("filename %r not found" % name)
KeyError: "filename 'hello.json' not found"
```