PLD: split viewsets into separate classes
PLD: remove unused imports
PLD: use specific mixin imports
PLD: use separate classes for each model and model test
PLD: match class name to filename for test_api
PLD: update test viewsets module paths
PLD: mimic order of mixin superclasses, this is important
Merge pull request #52 from onaio/pld/split-api-view-classes

PLD: split viewsets into separate classes, I figured it out, the order of the mixins was important