Installation with no s3 available

[bnlawrence]

ideally we'd S3netcdf could be tested for the CFA handling without the presence of an S3 host. There is no information as to how to configure S3NetCDF in that situation.

[nmassey001]

@bnlawrence the tests in test_s3Dataset do not require a S3 host to run.
They create the test files at:
path_stub = os.environ["HOME"] + "/Test/s3Dataset_test"
At the moment it doesn't create the "Test/" directory.