Implement alternative panel content storage (experimental)

[potzenheimer]

Provide a less content dependent storage for content panels by adding a small json storage layer. Most of the infrastructural bindings could easily be adopted from customer projects like rms or the ade25.assetmanager approach.

[Update 04.08.2016]

Since sentry logs errors steaming from unauthorized access to the panel objects using a simple and clean JSON data storage might also serve to resolve these issues.

Taking the idea even further we might need to deal with the content assets in a different manner, also storing uploaded images inside the panel page might still work as expected.

[potzenheimer]

A deliverable could be a storage.py tool that just deals with setting/getting and normalizing the JSON contents while providing a behavior for storing the Page data in a string or potentially file object.