Add swift:4.2 in default deployment

[csantanapr]

Fixes #4209

[codecov-io]

Codecov Report

Merging #4210 into master will decrease coverage by 4.8%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4210      +/-   ##
==========================================
- Coverage   86.02%   81.22%   -4.81%     
==========================================
  Files         152      152              
  Lines        7279     7290      +11     
  Branches      463      476      +13     
==========================================
- Hits         6262     5921     -341     
- Misses       1017     1369     +352

Impacted Files	Coverage Δ
...core/database/cosmosdb/RxObservableImplicits.scala	0% <0%> (-100%)	⬇️
...core/database/cosmosdb/CosmosDBArtifactStore.scala	0% <0%> (-95.54%)	⬇️
...sk/core/database/cosmosdb/CosmosDBViewMapper.scala	0% <0%> (-92.6%)	⬇️
...whisk/core/database/cosmosdb/CosmosDBSupport.scala	0% <0%> (-83.34%)	⬇️
...abase/cosmosdb/CosmosDBArtifactStoreProvider.scala	0% <0%> (-62.5%)	⬇️
...in/scala/org/apache/openwhisk/common/Counter.scala	40% <0%> (-20%)	⬇️
...in/scala/org/apache/openwhisk/common/Logging.scala	85.57% <0%> (-4.33%)	⬇️
...penwhisk/core/database/cosmosdb/CosmosDBUtil.scala	92% <0%> (-4%)	⬇️
...whisk/connector/kafka/KafkaMessagingProvider.scala	70.27% <0%> (-3.26%)	⬇️
...isk/core/controller/actions/PrimitiveActions.scala	85.71% <0%> (-1%)	⬇️
... and 7 more

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[csantanapr]

@rabbah thanks for the review, I updated the docs.
Let me know if you want anything else changed.