Framework requires OBS data configured even if the POD does not require it

[aradhakrishnanGFDL]

This would just make the errors more meaningful and appropriate, in addition to reducing the number of steps needed to run a POD that does not involve OBS

If OBS data is not in the user input configuration file, framework should print a warning and move on**

Creating a dummy OBS_DATA_ROOT directory

The POD I tested was the example_multicase which does not use OBS datasets in the present form. This may be the case for many case vs case comparisons, so having a user configure obs datasets seems to be a bit of an inconvenience, but not too bad if a workaround can be documented in the docs

To reproduce the issue, refer to example_multicase POD and use the sample configuration provided, with and without obs specifications.