Add control of session state

[alex268]

Current implementation of sessions and the session pool doesn't include the control of the session state. And we often have next problems:

1. Usage of session after closing
2. Parallel usage of one session
3. Deleting session by client error or canceling

We can resolve these problem by adding the control of current session state - idle, active, executing, canceled and etc. And every action on the session can check this state and returns an error if client uses session in wrong way