Add user viewable output for Spring Cloud Config option --configuration-cloud-config

[ccheetham]

Add some kind of output so that a developer can see Spring Cloud Config behavior in action.

Brief discussion with @bart-vmware and @dtillman led to ideas which include:

• adding output to the WeatherForecastController or a new controller
• adding log output

The first option of outputting via controller could potentially result in unintended exposure of sensitive information. Perhaps low risk, but nonetheless not zero.

The second option requires additional documentation in both the template and any docs that describe the feature in templates or the Initializr, such as the Steeltoe guides.

Perhaps the best option is a hybrid of the 2 above. Create a new controller that when invoked, logs a message with config artifacts and instructs the developer to view the logs and what to look for.

[ccheetham]

Completion of this issue should trigger an update to the corresponding guide in SteeltoeOSS/Documentation