Fix /proc/cmdline parsing when newline characters are present

Should fix bnc#887844
What about using native Ruby `split` with regexp argument?

```ruby
options = cmdline.split(/\s/)
```

Then you even do not need the `chomp` call, from `irb`:
```
irb(main):001:0> "dsa sa ds\nad d  \n\n  ".split(/\s/)
=> ["dsa", "sa", "ds", "ad", "d"]
```