Various Test & PSR-2 Updates

- Bring the code-base inline with the PSR-2 standard using
PHP_CodeSniffer
- Update Test HTTP adapter to store one or more HTTP requests
- Add in PHPUnit configuration values to test where superglobal values
are used
Readme to PSR-2
Remove un-needed extra empty lines from code
Add Coding Standard Fixer Config

Add in .php_cs configuration file for running @fabpot's PHP-CS-Fixer
Add .gitattributes file to ignore certain files when creating archives
Final PSR-2 layout / autoloading updates

- Rename namespace from GASS to Gass
- Move main GoogleAnalyticsServerSide class inside Gass namespace
- Implement SplClassLoader rather than proprietary one
Remove un-required variable
Temporary directory move so can get it named correctly on case sensitive file systems
Move to correctly named directory on case sensitive file systems