Renaming reports when there is only one report

The reports from the tests are saved in a folder named from the test class
Tried adding scripted-sbt for testing SBT plugin
Check if destination folder exists when processing single file
Use the parent folder when there is only a single report
Changed how coverage files are stored

Pattern is
    target/jscover/class-method/jscoverage.json
When merging reports, create destination folder if necessary
Pass complete files when merging
Copy original-src to report folders before merging
Close streams after copy
Close streams after copy. fixes #1