[feature-request] Enable report JUnit format

[v1v]

The idea is to enable this particular feature to be consumed by any CI automatically. It might be interesting to also list the files which were licensed validated too

Current format:

Call

go-licenser -d

Output

folder/y/foo.java: is missing the license header

Proposal format:

Add -junit flag to enable the output to be generated in the stdout.

Call

go-licenser -d -junit

Output

<?xml version="1.0" encoding="UTF-8"?>
<testsuite name="Licenses" time="50">
  <testcase name="bar.groovy" classname="folder.x" time="0"/>
  <testcase name="foo.java" classname="folder.y" time="0">
    <error message="folder/y/foo.java: is missing the license header"></error>
  </testcase>
</testsuite>

UI View in Jenkins (as an example)

The JUnit schema can be found below:

• https://stackoverflow.com/questions/4922867/what-is-the-junit-xml-format-specification-that-hudson-supports