style: normalize end of files

By PSR2 PHP Standard, the files should ends with exactly one newline.
Some of our files have 2 or more and some other were missing a newline.

Fix almost all occurences of CodeSniffer sniff:
PSR2.Files.EndFileNewline.TooMany

I have not fixed the selenium files, I believe we will drop them.

Change-Id: I89fca8c1786fee94855b7b77bb0f364001ee84b6