title: sbt-scoverage's coverageExcludedPackages does not exclude packages
body: <p>I'm using sbt scoverage 1.3.5 (Scala 2.11.8) and I have a bunch of classes that I do not want to include the the coverage reports. In particular the base classes and their tests are located in <code>com/corp/something/something_else</code> in both main and test. I have added the following lines to my buld.sbt:</p>
  
  <pre><code>coverageEnabled := true
  coverageMinimum := 90
  coverageFailOnMinimum := true
  coverageExcludedPackages := """com.corp.something.something_else.*;"""
  </code></pre>
  
  <p>I have tried it with single quotes and <code>\\.</code> in place of the dots, with and without the final <code>.*</code> and with and without the final semicolon but so far when I run <code>sbt clean coverage test coverageReport</code> the report contains everything and it does not exclude the packages I have listed. What am I missing?</p>
  
  <p>Perhaps in a similar vein is that the coverage report does not fail even though across all packages the coverage is below 90% and it should fail based on the option I set, right?</p>