Unify storage keys

[fsmanuel]

• Use : to delimit key parts
• Fallback to - delimiter
• Make it configurable (via environment.js)
• Make it possible to prepend a namespace

[ruzz311]

Rather than force a delimiter (such as ':' or '-' suggested above), could you allow configuration of the delimiter? If non is configured, then fallback to one of the two options?

[fsmanuel]

@ruzz311 sure! I'll keep that in mind when I implement it.

[fsmanuel]

@ruzz311 after almost a year I found some time to implement a namespace option that uses a configurable delimiter. It does not yet use the delimiter for the other key parts as that would require a migration mechanism for existing keys. I think about a follow up PR to do that. If you still use the addon and have some time I would appreciate a review for #279