ignore too early / too late attestations instead of penalizing them (#1608)
ignore too early / too late attestations instead of penalizing them (#1608)

## Issue Addressed

NA

## Proposed Changes

This ignores attestations that are too early or too late as it is specified in the spec (see https://github.com/ethereum/eth2.0-specs/blob/v0.12.1/specs/phase0/p2p-interface.md#global-topics first subpoint of `beacon_aggregate_and_proof`)




sigp/lighthouse,sigp/lighthouse,sigp/lighthouse,sigp/lighthouse