[#121] Remove django-cacheback

Remove code that used django-cacheback and its pip dependencies.

Remove unused imports in api/resources.py and reshuffle the importing
statements some.
[#240] Remove dependencies used by django-cacheback

Cacheback had quite a few dependencies that aren't needed any more
[#224] Expose unpublished projects in project API resource

To be able to query the API when determining how to handle the
uploading of IATI formatted data we need access to unpublished projects
through the API.

Implementation works as follows:

Un-authenticated users have access to published projects only, as before.
An authenticated user also has access to unpublished projects that
would be accessible in the admin:
  - Superusers and Akvo staff groups members get access to all projects
  - Partner's users get access to their "own" unpublished projects

This is implemented by adding ProjectResource.get_object_list() and
Project.of_partner()
[#224] Refactor resources.py into its own module

Split resources.py into separate files under api/resources.
Some resources are grouped in one file based on sharing of the
underlying model or function of the resource.
First commit of cordaid_org_importer.py script.
Merge branch 'feature/iati_update' of github.com:akvo/akvo-rsr into develop
[#250] Various improvements to cordaid_org_importer.py script. Now using .format() method and Python 3 print() calls.
[#250] Fix to Cordaid organisation creation script

Fix misspelling of variable name

Change the etree method for parsing the org XML
Merge branch 'release/2.1.5' into develop
Merge branch 'develop' of github.com:akvo/akvo-rsr into hotfix/2.1.5.1
Update Release Notes Closes#250
Closes #250
[#224] Add benchmarks to XSLT

Add selectors under result/indicator that turn into RSR benchmarks.
[#224] Add IATIBenchmarkResource

Add IATIBenchmarkResource to be able to process indicators in the IATI
XML and turn them into RSR benchmarks.
[#224] Add IATICategoryResource

Add IATICategoryResource to be able to create Project.categories
correctly from the IATI XML.
[#224] Add new resources to api/resources/__init__py
[#224] Remove org creation when posting IATI XML

Since all organisations now are created by an external script to
include more data about them, stop creating organistions from XML data
and instead raise an exception.
[#224] Add IATIProjectResource.benchmarks and
IATIProjectResource.categories

Add new toManyFields to IATIBenchmarkResource and IATICategoryResource

Extend alter_deserialized_detail_data() to massage the data needed for
the new fields
[#224] Better log output from the cordaid IATI XML loader script

The script now only uploads data for new projects.
[#224] Add scripts for Cordaid data

Add script to generate becnhmarknames for cordaid along with categoris for those

Add script to set Cordaid as funder to projects that aren't fully funded

Better output from the Cordaid org loader script