Removing trailing whitespaces

When using PhpStorm it always (there is an option not to do that, but it's enabled by default) trims whitespaces at the end of the lines. Not all PHP files in a project where changed after such auto-trim option was introduced in PhpStorm and because of this doing non-trim related changes always creates a noisy changes related to trailing whitespaces being removed.

Here I'm creating a special PR to remove all trailing whitespaces out there.