Reorganize "Settings-TestEnvironment" test to avoid duplication of data
Add "path env. variable" case to TestLauncherAdditionalSettings tests
Ensure 'additionalPathVariables' is not overridden. Fixes #56

Commit 714981 generalized how environment variables dealing with paths
were managed. This commit fixes a regression where environment variables
set in the main settings file where not considered is additional settings
where found.
Merge branch '56-fix-support-for-additional-env-pathvariables'

* 56-fix-support-for-additional-env-pathvariables:
  Ensure 'additionalPathVariables' is not overridden. Fixes #56
  Add "path env. variable" case to TestLauncherAdditionalSettings tests
  Reorganize "Settings-TestEnvironment" test to avoid duplication of data