Express session bug

Running tests on the 0.2.3 master produced this warning and the mocha tests would not run.

Running "mochaTest:src" (mochaTest) task
Warning: Cannot read property 'Store' of undefined Used --force, continuing.

Found a workaround for the warning at http://stackoverflow.com/questions/23005971/upgrading-from-express-3-x-to-express-4-x-mongo-session-store