Prevent path/param drop when both fields have the same name.

[ghost]

Attempt to fix #137. While this might not be the best way, it demonstrates extracting path parameters first.

[thinkwelltwd]

@hurturk, that's working for me!

@tomchristie, would there be some way to specify a path param separately from the field params, so that the lookup_field value could be updated just as an HTML form?

[ghost]

Doc generated cli command already show two consequent parameters with same name fyi. Alternative solution would be to take first one as a path and the later as data.

Or if lookup_field can be used in a way just like the example in the coreapi-cli readme:

coreapi show notes 0 description

Here, instead of 0, I think lookup_field could be used? I can certainly make another PR for that when decided.