Allow field to be used in shortcode in other cases

If someone tries to use:
[pods name="podname" where="t.somthing = 'else'" field="test"]
it won't work, although this does work
[pods name="podname" where="t.somthing = 'else'"]{@test}[/pods]

I understand why they work differently but I don't see a reason not to allow this usage
Merge pull request #2339 from jamesgol/shortcodewithoutid

Allow field to be used in shortcode in other cases