Context:
The way it's currently implemented, the light client needs to sync all blocks from genesis, which, depending on the number of blocks and the environment the light client is running in, can easily take more than 24h for chains with a slightly larger number of blocks.
This will make the light client basically un-useable for occasional or one-time users who don't keep a synced version of their selected chain in the IndexedDB.

Goal
Get initial sync duration of the Light Client down to 60sec.

Proposed solution:

• Provide checkpoints snapshots in the chainspec (like we did on parity-ethereum / open-ethereum //by @andresilva )