Accept a { with no space before block arguments

The current Cop `SpaceAroundBraces` takes offence by this code:
```ruby
%w(yes no).each {|word| word.upcase }
```
saying "`Surrounding space missing for '{'.`", i.e. recommending:
```ruby
%w(yes no).each { |word| word.upcase }
```
This PR makes `SpaceAroundBraces` accept the first version too.

Should this be a configurable option?