drop the dependency on knesset-data-datapackage

[OriHoch]

suggested changes to PR hasadna#9:

• dropped the dependency on knesset-data-datapackage
  • this over complicated things
  • support scraping only from a pre-created datapackage zip file
  • use the datapackage schema json file to determine field types
• skipped the datapackage test
  • it was very fragile, need to think how to make it less fragile

[OriHoch]

https://travis-ci.org/OriHoch/knesset-data-django/builds/251420209

[OriHoch]

https://travis-ci.org/OriHoch/knesset-data-django/builds/251420901