Development Environment Flexibility and Continuous Integration Enhancements

Changed phpunit.xml to phpunit.xml.dist for portability and allowing for environment overrides. Enhanced the .gitignore for wider handling of diverse development environments. This should fix Celc/CIUnit#11
Shouldn't the same thought process apply to the .DS_Store line as well then? Seems like that is a platform specific ignore, which in my case (developing on Linux) is useless as well. I'm fine will your comments in general I just tend to be a bit more inclusive then exclusive with gitignore.