Disabling automatic refresh for snap from store

[ogra]

@mlopezqc

Guess what, snap was happily updating itself over my data plan

This has already been fixed (but not fully enabled by default yet as i understand) via:

Snap refresh over metered connections

Rationale In the lengthy topic about disabling snap refresh, a user bought up this: NetworkManager is widely used across all major Linux distributions, I thought it might be useful to at least test the waters and so some digging and come up with a proposal. Limited data plans are unfortunately a thing. A user with several GB data plan, tethering wifi from her phone, may not want snaps to get refreshed in such conditions. Similarly, a device with a fallback link over 3G may similarly, inhibit …