Update README to explain that Reek can't parse new Ruby 1.9 hashes

[jcf]

What do you think to explaining Reek won't be able to analyse files containing new 1.9 hashes? Does this belong in the README or else where?

[arwagner]

I appreciate you submitting this. Just curious, can you describe what problems you had with the syntax, though? ruby_parser doesn't blow up when it tries to parse it:

/Users/andrewwagner/ruby> echo '{a: 3}' > foo.rb
/Users/andrewwagner/ruby> cat foo.rb
{a: 3}
/Users/andrewwagner/ruby> reek foo.rb
foo.rb -- 0 warnings

On the other hand, it also doesn't successfully parse it:
ruby-1.9.2-p290 :001 > require 'ruby_parser'
=> true
ruby-1.9.2-p290 :002 > RubyParser.new.parse "{a: 3}"
=> nil

What behavior did you see? Thanks again!