Squashed commit of the following:

[rlan35]

commit dc036e6
Author: Ganesha Upadhyaya ganeshrvce@gmail.com
Date: Sun Apr 5 17:18:36 2020 -0700

fix earned-reward by writing the stats only once, remove from UpdateValdiatorVotingPower (#2737)

commit 66f26e8
Author: Rongjian Lan rongjian.lan@gmail.com
Date: Sun Apr 5 17:06:50 2020 -0700

do snapshot for validators at last block of epoch (#2736)

commit f2524a8
Author: Rongjian Lan rongjian.lan@gmail.com
Date: Sun Apr 5 12:33:35 2020 -0700

Make validator snapshot on new validator too (#2733)

commit 350b7a0
Author: Rongjian Lan rongjian.lan@gmail.com
Date: Sat Apr 4 23:41:19 2020 -0700

fix validator snapshot cache

commit 8f5f287
Author: Leo Chen leo@harmony.one
Date: Sat Apr 4 19:09:38 2020 -0700

[node.sh] use rclone to fast sync harmony_db_0 (#2709)

Signed-off-by: Leo Chen <leo@harmony.one>

commit 05f2e20
Author: Rongjian Lan rongjian.lan@gmail.com
Date: Sat Apr 4 19:00:28 2020 -0700

make validator snapshot consistent with election (#2726)

* make validator snapshot consistent with election

* fix condition with only beacon chain

* Fix epoch number

* Fix stats update nil epoch issue

commit 24a17fe
Author: Edgar Aroutiounian edgar.factorial@gmail.com
Date: Sat Apr 4 16:38:12 2020 -0700

[state] ValidatorWrapper div zero panic fix -  (#2724)

* [state] Error on div zero

* [state] Do not pay out commit when commit is 0%

* [state] Put whole commission in guarded block

* [core] Reward cannot be zero

* [state] return nil, not hard error

commit 1f83ebf
Author: Minh Doan 40258599+mikedoan@users.noreply.github.com
Date: Sat Apr 4 14:38:55 2020 -0700

change explorer node storage folder (#2720)

commit 3aa08e9
Author: Edgar Aroutiounian edgar.factorial@gmail.com
Date: Sat Apr 4 10:21:51 2020 -0700

[rpc] Show both latest header of beacon chain and shard chain (#2714)

commit 1a2c23a
Author: Edgar Aroutiounian edgar.factorial@gmail.com
Date: Fri Apr 3 17:49:24 2020 -0700

[validator] Hide one field from JSON (#2705)

Issue

Test

Unit Test Coverage

Before:

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After:

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Test/Run Logs

Operational Checklist

1. Does this PR introduce backward-incompatible changes to the on-disk data structure and/or the over-the-wire protocol?. (If no, skip to question 8.)

   YES|NO

2. Describe the migration plan.. For each flag epoch, describe what changes take place at the flag epoch, the anticipated interactions between upgraded/non-upgraded nodes, and any special operational considerations for the migration.

3. Describe how the plan was tested.

4. How much minimum baking period after the last flag epoch should we allow on Pangaea before promotion onto mainnet?

5. What are the planned flag epoch numbers and their ETAs on Pangaea?

6. What are the planned flag epoch numbers and their ETAs on mainnet?

   Note that this must be enough to cover baking period on Pangaea.

7. What should node operators know about this planned change?

8. Does this PR introduce backward-incompatible changes NOT related to on-disk data structure and/or over-the-wire protocol? (If no, continue to question 11.)

   YES|NO

9. Does the existing node.sh continue to work with this change?

10. What should node operators know about this change?

11. Does this PR introduce significant changes to the operational requirements of the node software, such as >20% increase in CPU, memory, and/or disk usage?

TODO