Session keys should be case-INsensitive to match default ASP.NET behavior, or at least configurable #20
Description
When switching from StateServer to RedisSessionProvider, I found that you're handling session keys case-sensitively, because you're using the default ConcurrentDictionary IStringEquality behavior.
MSDN docs don't specify, but at least based on Internet discussions: http://stackoverflow.com/questions/1731283/net-httpsessionstate-case-insensitivity that to match classic ASP behavior, session keys along with other ASP.NET collections are case-insensitive.
To fix, all constructors need the following:
this.Items = new ConcurrentDictionary<string, object>(concLevel, numItems, StringComparer.InvariantCultureIgnoreCase);
this.SerializedRawData = new ConcurrentDictionary<string, string>(StringComparer.InvariantCultureIgnoreCase);