Fix for #19: SessionManager and custom SessionFactories

Signed-off-by: Bryan Robbins <bryantrobbins@gmail.com>
Fixing merge conflict in SessionManager (typo in error message)

Signed-off-by: Bryan Robbins <bryantrobbins@gmail.com>
Merge pull request #20 from bryantrobbins/master

Fix for #19: All unit/integration tests passed