Cannot convert collection retrieved with cURL

[weskoerber]

When exporting a collection with the Postman Web and Desktop clients conversion completes successfully. However, when using the curl command, conversion fails.

@justinyoo discovered in #120 that this was due to another wrapper attribute called collection in the json response. I've confirmed this to be the case. p2o converts the collection successfully after removing the collections wrapper attribute.

I'm trying to use curl in a script with p2o to automate documentation updates, and it would be really nice if we had support for collections with this extra wrapper attribute!

[joolfe]

Merged, Thanks!