issue91 clearing session table after each test | Approach 'B'

[karliatto]

Approach B for:

• Modified tearDown function in 'test/manager.js' to clear sessions as suggested using 'express-session' module.

in this approach using variable 'app' instead of requiring each module again in 'test/manager.js'

app.sessionStore = new MySQLStore(app.config.db);

This one seems better to me