Move confluent_kafka/ to src/ to avoid pytest/tox picking up the local dir

.. rather than the installed module.

Should once and for all eliminate the "ImportError: .. confluent_kafka.cimpl"
problems.

Author: edenhill

MANIFEST.in

@@ -1,4 +1,4 @@
 include README.md
 include LICENSE.txt
 include test-requirements.txt
-include confluent_kafka/src/*.[ch]
+include src/confluent_kafka/src/*.[ch]

setup.py

@@ -6,7 +6,7 @@
 import platform
 
 work_dir = os.path.dirname(os.path.realpath(__file__))
-mod_dir = os.path.join(work_dir, 'confluent_kafka')
+mod_dir = os.path.join(work_dir, 'src', 'confluent_kafka')
 ext_dir = os.path.join(mod_dir, 'src')
 
 INSTALL_REQUIRES = [
@@ -70,7 +70,8 @@ def get_install_requirements(path):
       author_email='[email protected]',
       url='https://github.com/confluentinc/confluent-kafka-python',
       ext_modules=[module],
-      packages=find_packages(exclude=("tests", "tests.*")),
+      packages=find_packages('src'),
+      package_dir={'': 'src'},
       data_files=[('', [os.path.join(work_dir, 'LICENSE.txt')])],
       install_requires=INSTALL_REQUIRES,
       extras_require={