upgrade opening netcdf files method

[kwhitehall]

There was a suggestion to extend the netcdffile read methods e.g. NetcdfDFSFile, to ensure maximum time series on the partition during the read. Initially a flag can be added, that would (1) ensure the URI list is sorted according to time within the filenames; (2) deploy a private method to sort the list on the partition ahead of any other transformations.

[rahulpalamuttam]

How about not just having it sorted, but also paired.
We could then go from RDD[(URI, Next URI)] => RDD[(SciTensor, Next SciTensor])

We would only be shuffling small URI strings when we sort and pair and will not be shuffling around
the array bundle.

[rahulpalamuttam]

Actually pairing up the URI's brings in extra overhead of reading each HDFS file twice.
Let's just sort the URI's and read each file once.