renamed test classes so that they execute under maven
faster travis builds with sudo:false
cleanup of pom.xml

* Updated versions of plugins
* Restricted scope of test plugins
* removed unused plugins
Removed priority strategy and need to sort rulesets
completely removed priority at rule level
Updated the antlr sources as well.

The generated files were modified directly in the last commit
without updating the antlr files
Merge pull request #9 from UprootLabs/counterLess

Priority-less and Counter-less. Fix for issue #60. Test fixes.
Avoid exception when no indices specified for nth-child selectors