Review logged messages

[aspnet-hello]

From @JunTaoLuo on Wednesday, October 5, 2016 6:06:13 PM

Review the messages that are logged added in aspnet/ResponseCaching#65. Also make sure the messages are at the correct level.

Copied from original issue: aspnet/ResponseCaching#68

[aspnet-hello]

From @muratg on Thursday, May 25, 2017 3:39:06 PM

@glennc Are you able to look into this for preview2, or should we move it out to preview3.

[JunTaoLuo]

Doesn't look like we need this anymore.