Tell Hound to allow {} for multi-line blocks

Prefer alternate convention based on semantic intent of block. See:
http://devblog.avdi.org/2011/07/26/the-procedurefunction-block-convention-in-ruby/

See: https://github.com/bbatsov/rubocop/blob/master/config/enabled.yml#L81

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #1944 from opf/fix/houndci-allow-braces-multiline-blocks

Tell Hound to allow {} for multi-line blocks