API for Dataset/Dataset Member Allocation

[timgerstel]

This pull request implements the following feature:

• API which enables the allocation of datasets and dataset members.
• Add 'PUT' method to /datasetContents, accepts JSON body to specify dataset parameters
• Sample request body:

{
   "ndisp": "CATALOG",
   "status": "NEW",
   "dsorg": "PS",
   "blksz": "27998",
   "lrecl": "84",
   "recfm": "V",
   "close": "true"
}

[lchudinov]

The code looks good to me now. I have a question: don't we need to unallocate the dataset? Did I miss the call that unallocated the dataset?

[lchudinov]

I approve this because it's a new feature, but we need to deallocate the dataset at the end of the request.