check for required coverage and report summary
check isNan for coveredRatio
unit tests for Report.scala
introduce Thresholds class, fix unit tests and some other changes to address Joachim"s comments
play with existing system tests - add thresholds in the test configuration
run sbt.bat only in Windows and sbt otherwise (in tests)
Merge pull request #17 from apismensky/master

Added report summary to the build output and check for required coverage