Storage API for accessing shared variables in Command classes

[dotchetter]

Accessing a Storage API inside Command class implementation is evident.

Using Command classes encapsulates and isolates the logic for a single command.
Sometimes however, the context of data parsed or stored by other commands is needed
to fully execute a command.

A Storage API in Pyttman could solve this situation by providing developers a way to access
data encapsulated on Feature and App level, making various features able to share
data between them for different context.