Improve JUnit report

Now something more complex and probably needing more thorough review. All the commits here are created to make Jenkins test results presentation for lintian more useful. The tests are grouped by package under test and named after lintian tags (+ tag arguments). Ouput from lintian is parsed a bit more in order to attach meaningful part of it to specific test cases. And the final small change fix the problem with time reported as actual lintian run time multiplied by number of failing test cases.

Oh, and this time I've also checked it with Ruby 1.8 (that is 1.8.7).