CDK-537: Check for empty views and return 0 splits.

This updates the FS implementation's InputFormat to check the incoming
view using isEmpty to fix the setInputPaths bug. FileInputFormat assumes
that setInputPaths is called with at least one path. MR tests have been
added for both FS and HBase.
Merge pull request #144 from rdblue/CDK-537-fix-mr-empty-views

CDK-537: Check for empty views and return 0 splits.