Logging API changes

[BrennanConroy]

The Log... functions are now in 3 flavors

• Log....(this ILogger logger, EventId eventId, Exception exception, string message, params object[] args);
• Log....(this ILogger logger, EventId eventId, string message, params object[] args);
• Log....(this ILogger logger, string message, params object[] args);

ILogValues was removed and we are using IReadOnlyList<KeyValuePair<string, object>> instead

void Log(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter) is now void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)

The default MessageFormatter now only displays the string value of the state passed in

See the original issue aspnet/Logging#331

For discussion use aspnet/Logging#350