add demoapp to release package and clean up files being distributed from the test directory

MANIFEST.in

@@ -1,6 +1,7 @@
 include setup.py
 include distribute_setup.py
-include tests/*
 recursive-include docs *.rst *.py *.html *.css *.js *.png *.txt
+recursive-include demoapp *.py
+recursive-include tests *.py
 include tox.ini