Upgrade nmslib to 2.0.11

[jmazanec15]

Issue #, if available:
#290

Description of changes:
PR upgrades nmslib from 2.0.8 to 2.0.11. 2.0.8 was deleted because of build failure for python bindings. Core code was not changed between update from 2.0.8 to 2.0.11.

gradle build was passing.

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[codecov]

Codecov Report

Merging #302 (4b5a316) into master (79f7748) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master     #302   +/-   ##
=========================================
  Coverage     80.51%   80.51%           
- Complexity      388      389    +1     
=========================================
  Files            62       62           
  Lines          1468     1468           
  Branches        130      130           
=========================================
  Hits           1182     1182           
  Misses          239      239           
  Partials         47       47           

Impacted Files	Coverage Δ	Complexity Δ
...istroforelasticsearch/knn/index/KNNIndexCache.java	92.30% <ø> (ø)	35.00 <0.00> (ø)
...istroforelasticsearch/knn/index/KNNIndexShard.java	92.00% <ø> (ø)	10.00 <0.00> (ø)
...pendistroforelasticsearch/knn/index/KNNWeight.java	97.14% <ø> (ø)	10.00 <0.00> (ø)
...index/codec/KNN80Codec/KNN80DocValuesConsumer.java	70.88% <ø> (ø)	15.00 <0.00> (ø)
...forelasticsearch/knn/index/util/NmsLibVersion.java	100.00% <100.00%> (ø)	2.00 <0.00> (ø)
...stroforelasticsearch/knn/index/v2011/KNNIndex.java	76.74% <100.00%> (ø)	8.00 <1.00> (?)

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[vamshin]

LGTM!