Session state used to persist view mode in settings control

Description

Configuration base classes used by the MAI framework are using the session to store button states. When
enableSessionState is false, the following error is displayed in the configuration.
Session state can only be used when enableSessionState is set to true
This is in common code found in the framework module. The issue was first seen with the Silverpop connector.

Steps to reproduce
1) Install the Alloy sample application and the latest 5.x framework with the Silverpop connector.
2) Verify that the configuration page is visible and works properly for the Silverpop connector.
3) Shut down the application.
4) In the web.config file, change the enableSessionState variable to false. For example:

<pages enableEventValidation="true" enableViewState="true" enableSessionState="true" enableViewStateMac="true"> 

should be modified to

<pages enableEventValidation="true" enableViewState="false" enableSessionState="true" enableViewStateMac="true">

5) Run the Alloy app again.
6) Note that the Silverpop connector cannot be configured, and the message is displayed "Session state can only be used when enableSessionState is set to true."