Create service in YAML format should use space instead of tab

[leo108]

It's recommended to use space instead of tab in YAML format

[veloxy]

I agree, it's stated in the Symfony docs to always use spaces:

There is one important thing you need to remember when using indentation in a YAML file: Indentation must be done with one or more spaces, but never with tabulators.

[veloxy]

Also, this is a duplicate of #533

[Haehnchen]

done