Sqoop2: Provide simple test that can validate if connector is reasonably formed

On internal hackathon we we're hacking Sqoop 2 connector with singhashish and we went through few troubles that we should address.

We have a lot of requirements for Sqoop connectors that are only documented but not enforced by the code, for example:

• Resource bundles need to have names for all properties in configuration objects
• Configuration objects needs to be properly annotated

If either of those is incorrect then we happily load the connector just to throw some random exceptions during runtime. We should provide simple test case that all connectors can reuse to validate that connector is properly formed as Sqoop expects.

(Which still doesn't mean that the connector will work as we can't guarantee that extractor/loader is properly implemented. But we can at least help people to not see random exceptions such as those described in SQOOP-2494).