Added Lines Before Namespace Fixers

NoBlankLinesBeforeNamespaceFixer is a contrib level fixer, and OneBlankLinesBeforeNamespaceFixer is a symfony level fixer. This also includes some utils refactoring and improvements.
The tests do?

>  Indeed it was designed for docblocks, so method rename might be wise

I didn't originally name the method, but I'm happy to rename it, and it definitely needs a better description, you're right. What would you suggest? I'm happy to change it. :)