0.5.0

WARNING: Huge API changes in this release, please check CHANGELOG.md

• Change: Use native django.form.fields if possible
• Change: Removed kwargs propagation from release 0.3.0
• Change: Changed syntax back to django.forms compatible (e.g. form.validate_{key}() -> form.clean_{key}())
• Change: FieldList raises ValidationError instead of RuntimeException if there is a type in validation
• Change: Use private properties for internal data in field objects
• Fixed: FieldList returns values instead of None
• Fix: Fixed validation in DictionaryField
• Maintenance: Basic unit tests