EntityFranework Connection Management

https://msdn.microsoft.com/en-us/library/bb896325(v=vs.100).aspx

https://msdn.microsoft.com/en-us/data/dn456849.aspx

http://stackoverflow.com/questions/5285877/closing-connections-explicitly-in-entity-framework

http://stackoverflow.com/questions/19847248/entity-framework-v6-closes-connections-after-exception-without-using-statment

http://stackoverflow.com/questions/1282675/when-does-entity-framework-open-and-close-database-connections