import curl_plugin_shared with path magic to unbreak python3.2

Summary:
D38 broke the build (just for python3.2) because it imported code from
directories without `__init__.py` files. D40 tries to fix this by adding those
files, which is pretty ugly, because e.g. `resources` really shouldn't be
thought of as a Python module. This diff is an alternate fix, modifying
`sys.path` instead of adding new files.

Test Plan: Push a test branch to GitHub for Travis.

Reviewers: sean

Differential Revision: https://phabricator.buildinspace.com/D41