Rename SpaceAroundBraces: SpaceAroundBlockBraces

Remove code checking hash literals from SpaceAroundBlockBraces, and
improve the the cop's test coverage.
Add config option for SpaceAroundBlockBraces

With `NoSpaceBeforeBlockParameters` set to true, we require zero
spaces between { and | in blocks taking parameters.
Merge pull request #465 from bquorning/space-between-brace-block-and-arguments

Accept a { with no space before block arguments