Add a new IntegrationTestHelper class for buckets.

[1010sachin]

Goal

The goal of this PR is to provide a test helper class that can be use to extend the current Integration Test suite to test buckets api, when they are ready.

Implementation

• Introduce a new TestNG parameter, called String testType that when set to the value buckets will setup up the bucketsTestPathPrefix to the required bucket format i.e. /$MANTA_USER/buckets/bucket_name and the testPathPrefix to /$MANTA_USER/buckets/bucket_name/objects/object_name.
• Introduce a new helper class, called IntegrationTestHelper.java that contains utility methods to verify whether the MANTA server supports the buckets API, configure the paths to test the buckets and bucket objects API in the test classes and clean up the bucket and objects after execution of the test cases.

NOTE This PR contains changes in the MantaClientIT.java to show the use of the class IntegrationTestHelper. The same changes can be propagated to the other classes when the buckets API code is ready for testing.

[indianwhocodes]

Merely a suggestion but you could update the copyright headers for all the changed files.