adding has_tag? to the rmq selector

asking people to jump into `rmq_data` plumbing can get messy.  Best if RMQ api has a porcelain alternative

```ruby
rmq(my_view).has_tag?(:your_tag) #false
rmq(my_view).tag(:your_tag)
rmq(my_view).has_tag?(:your_tag) #true
```