hide prototyping tools in sv package

[SHuang-Broad]

but still runnable if knowing their existence

[tedsharpe]

Looks fine to me. I'm getting the Travis failure, too. Not your problem.

[codecov-io]

Codecov Report

Merging #3556 into master will increase coverage by 0.008%.
The diff coverage is 5.882%.

@@               Coverage Diff               @@
##              master     #3556       +/-   ##
===============================================
+ Coverage     79.928%   79.935%   +0.008%     
  Complexity     17900     17900               
===============================================
  Files           1199      1199               
  Lines          65015     65015               
  Branches       10124     10124               
===============================================
+ Hits           51965     51970        +5     
+ Misses          9016      9012        -4     
+ Partials        4034      4033        -1

Impacted Files	Coverage Δ	Complexity Δ
...v/evidence/experimental/FindSmallIndelRegions.java	0% <ø> (ø)	0 <0> (ø)	⬇️
...iscoverFromLocalAssemblyContigAlignmentsSpark.java	0% <0%> (ø)	0 <0> (?)
...y/prototype/SimpleStrandSwitchVariantDetector.java	33.588% <0%> (ø)	13 <0> (ø)	⬇️
...ry/prototype/FilterLongReadAlignmentsSAMSpark.java	55.652% <16.667%> (ø)	29 <0> (?)
.../main/java/org/broadinstitute/hellbender/Main.java	54.857% <0%> (-1.143%)	28% <0%> (-1%)
...er/tools/spark/sv/discovery/AlignmentInterval.java	88.889% <0%> (+0.463%)	52% <0%> (+1%)	⬆️
...oadinstitute/hellbender/utils/gcs/BucketUtils.java	79.87% <0%> (+3.896%)	39% <0%> (ø)	⬇️