Basic changes for repository health

[sateffen]

Hey,

this PR should provide some changes to provide a better repository health. The changeset is pretty small:

• Updates formatting of OWNER.md
  • The file was ill-formatted
• Updated CI-configuration
  • Added node6 and node8 as CI-targets, as they are the current LTS versions and should get covered
  • Added caching for npm to speed up builds
• Corrected 2 spacing-problems in sourcecode
• Set typescript transpile-target from ES5 to ES2016
  • As noted on node-green node6 in specified minimum version supports all of ES2015 and ES2016, so the target should set to the corresponding one to allow the node-engine all possible optimizations

[coveralls]

Pull Request Test Coverage Report for Build 115

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.3%) to 88.473%

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Totals
Change from base Build 112:	-1.3%
Covered Lines:	788
Relevant Lines:	882

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💛 - Coveralls