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.
We need to have exactly 2 lines here. The first is the opening tag. The second is the namespace. That's how you wanted the utils function to behave. I said I'd prefer to use 1 here, and count new line characters, but I we decided to go with this.