Update the KMIPProxy client to support batch processing

[PeterHamilton]

This change updates the KMIPProxy client to officially support batch processing. Passing 'batch=True' to any operation method will queue up the operation request. The entire queue will be sent when 'batch=False' is passed to an operation method. Instead of the single operation result, a list containing all operation results will be returned.

[codecov-io]

Codecov Report

Merging #404 into master will decrease coverage by 0.36%. The diff coverage is 52.74%.

@@            Coverage Diff             @@
##           master     #404      +/-   ##
==========================================
- Coverage   94.99%   94.63%   -0.37%     
==========================================
  Files          73       73              
  Lines       12228    12335     +107     
==========================================
+ Hits        11616    11673      +57     
- Misses        612      662      +50

Impacted Files	Coverage Δ
kmip/services/kmip_client.py	63.76% <52.74%> (-1.83%)	:arrow_down:

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