chore(style): removes trailing whitespace from code files

Let's end the madness.

BTW this was done by replacing `(\S)[ \t]+\n` with `$1\n` in PHPStorm.

TODOs:
- [ ] Add Travis check to prevent regressions
- [x] Add some kind of `fix_style` script that contributors can run to auto fix violations
- [x] Revert changes to files in `vendors` dirs
- [ ] Only run unit test on one Travis process
- [x] Filter out `node_modules` and other Travis build stuff