Add better `inspect` output for ExampleGroup

Pull Request for #1590 

The only problem I ran into was that the syntax error in the after hook test produces error output while running the spec (the test still passes).

> An error occurred in an `after(:context)` hook.
>   NoMethodError: undefined method `expcts' for #<RSpec::ExampleGroups::SomeClass_3 after(:context) hook>

This is definitely not ideal because it could distract from problems with "real" after hooks. The only two options I could up with were: 1) remove the test, or 2) add a way to suppress that error. I'm interested in your thoughts on the best way to handle this.
I think maybe @kcdragon is referring to a case where there are multiple hooks in the same context, like this?

```ruby
RSpec.describe do
  before(:context) { }
  before(:context) { }
end
```

...but I believe they are evaluated in the context of the same example group instance.  Assuming that's what you're talking about, @kcdragon, my vote is not to use the hook location in the description after all, since it's the instance isn't specific to one hook, but is rather for all `:context` hooks in the context...and given that, I think what you had before is fine.  Sorry to lead you astray :(.