Added license report task

The license report task dumps a markdown report to standard out to give
some indication of the state of licenses that Play projects are using.
initial commit
Merge pull request #1537 from jroper/license-report

Added license report task
Merge pull request #1542 from wsargent/1542-update-scalaws

[doc] More WS documentation, worked examples
Merge remote-tracking branch: upstream/master