Extension doesn't import files from zipped datapackages

If an user import a datapackage from a zip file and this zip has a resource file inside of it, the file is not created on CKAN. Instead a resource is created with a wrong URL. Example, with the following datapackage:

{
  "name": "datetimes",
  "resources": [
    {
      "name": "datetimes",
      "path": "data/datetimes.csv"
    },
    {
      "name": "timezones",
      "url": "http://www.somewhere.com/timezones.csv"
    }
  ]
}

There will be a resource called "datetimes" that will have a link to download it as http://data/datetimes.csv. The resource is being loaded correctly by datapackage-py library but there is no logic in the extension to add it as a resource

Please preserve this line to notify @amercader (lead of this repository)

frictionlessdata / ckanext-datapackager

Extension doesn't import files from zipped datapackages #86