Merge pull request #61 from maddingo/master

case error in coverageInputDatafile and coverageOutputDatafile
Fixed some more typos in the readme
fixed bintray upload
Changed the changelog into a Markdown file
Separated the usage into its own page for better linking from the Cobertura wiki
Added a dependency from the coberturaCheck task to the coberturaReport task to fix issue 63
prepend the instrumented_classes to all test tasks and don't bother removing the output files, a sourceSet might have several output paths and not all of them might be included in instrumentation. For Cobertura it is enough that the instrumented classes occure first