Remove test helpers and explicitly exclude other files from sdist

Author: pelme

MANIFEST.in

@@ -1,3 +1,15 @@
 include AUTHORS
 include README.rst
 include LICENSE
+
+recursive-exclude pytest_django_test *
+recursive-exclude tests *
+recursive-exclude .tox *
+recursive-exclude bin *
+recursive-exclude src *
+recursive-exclude .git *
+recursive-exclude bin *
+recursive-exclude include *
+recursive-exclude lib *
+recursive-exclude share *
+recursive-exclude src *