Feature + bug fix

Hi,

I'm making a pull request for 2 commits in log2jsconsole. The first one adds an entry point in the `setup.py` file so that the middleware can be used together with Python Paste. For example, this is the configuration file I used to test:

```ini
[app:main]
use = egg:pydap#server
root = %(here)s/data
templates = %(here)s/templates
x-wsgiorg.throw_errors = 0
filter-with = log

[filter:log]
use = egg:log2jsconsole
auto_install = True
```

The second commit is a bug fix. The replacement `start_response` function that was being created had the wrong signature (per PEP 333).