Fix style issues

Based on PullReview, fix some style issues.

I didn't fix spacing for bloc wrapped with {} as it seems to be done consistently, neither wrapped multiline bloc by `do ... end` (especially when a method is called on the result of the bloc). Should I?

Another question, in the contributing you mention you prefer single quote except when there is string interpolation. May I clean the string that don't respect that convention?

What about Hash syntax? which convention do you follow? because I've found both.