Work around broken resource_filename() on Google AppEngine

On Google AppEngine, resource_filename() is broken. Here I simply avoid using it.

Here is the stacktrace for your amusement:

```
  File "lib/deform_bootstrap-0.2.6-py2.7.egg/deform_bootstrap/__init__.py", line 21, in add_search_path
    resource_filename('deform_bootstrap', 'templates'),
  File "/home/fmaia/py/google_appengine/lib/setuptools-0.6c11/pkg_resources.py", line 882, in resource_filename
    self, resource_name
  File "/home/fmaia/py/google_appengine/lib/setuptools-0.6c11/pkg_resources.py", line 1352, in get_resource_filename
    return self._extract_resource(manager, zip_path)
  File "/home/fmaia/py/google_appengine/lib/setuptools-0.6c11/pkg_resources.py", line 1359, in _extract_resource
    manager, os.path.join(zip_path, name)
  File "/home/fmaia/py/google_appengine/lib/setuptools-0.6c11/pkg_resources.py", line 1373, in _extract_resource
    self.egg_name, self._parts(zip_path)
  File "/home/fmaia/py/google_appengine/lib/setuptools-0.6c11/pkg_resources.py", line 957, in get_cache_path
    extract_path = self.extraction_path or get_default_cache()
  File "/home/fmaia/py/google_appengine/lib/setuptools-0.6c11/pkg_resources.py", line 1080, in get_default_cache
    return os.path.expanduser('~/.python-eggs')
  File "/home/fmaia/py/venvs/v7/lib/python2.7/posixpath.py", line 268, in expanduser
    import pwd
  File "/home/fmaia/py/google_appengine/google/appengine/tools/devappserver2/python/sandbox.py", line 822, in load_module
    raise ImportError('No module named %s' % fullname)
ImportError: No module named pwd
```