[Suggest] Where table syntax by Refinement

In Ruby2.1, We can use `Module#using`.
And so, can use `using` inner ExampleGroup block.

I suggest "Where Table syntax by Refinement",
Because I want to reduce AST black magic.

Sample:
```ruby
describe "table separated with pipe (using TableSyntax)" do
  using RSpec::Parameterized::TableSyntax

  where(:a, :b, :answer) do
    1         | 2         | 3 >
    "hello "  | "world"   | "hello world" >
    [1, 2, 3] | [4, 5, 6] | [1, 2, 3, 4, 5, 6]
  end

  with_them do
    it "a plus b is answer" do
      expect(a + b).to eq answer
    end
  end
end
```

But, There is one probrem.
Refinement style need to tell next parameter line.
```ruby
    1         | 2         | 3 >
```
I use `>` as temporary.