README.md: fix usage example
JSONFieldBase: don't allow non-valid JSON data
DynamicModel: fix absence of _schema attr in super __init__
DynamicModel: remove get_field_dict method (unnecessary)
DynamicFormTest: update test after removing DynamicModel.get_field_dict method
DynamicModel: add field value to get_extra_fields iterator tuple
add tests for valid/non-valid JSON in DynamicModel.extra_fields
Merge pull request #6 from horva/fixes

Fixes
use cache backend to store schema
update tests
update models

- add instance method for getting cache key value and rename classmethod
(with same functionality) in DynamicSchema

- refactor DynamicSchema.renew_cache_static - fixes case when schema is
created for the first time so schema is cached without prefetched fields
clear cache after deleting schema
change ValueError to ValidationError so it can be handled by the form
fix string format
update admin display
fix DynamicSchema qs deletion
tests for prev commit
Merge pull request #7 from horva/cache-schema

Cache schema
refactor tests

no need to delete all db entries in setUp - django does it automatically
use assertNumQueries so there is no need for settings.DEBUG=True
move tests and admin code to testapp app