Update node and apply some fixes

- Node
	- Load Coordinator Fee Account from config
		- Sign the AccountCreationMsg to generate the
		  AccountCreationAuth
		- Resolve #465
	- Wait for synchronizer termination before stopping coordinator to avoid
	  getting stuck when closing in the following case:
		- The coordinator stops reading the synchronizer msg channel,
		  and the node gets stuck sending a message to that channel.
- Common
	- Move account creation auth signature code to common.
	- Update RollupConstInputSHAConstantBytes
- Coordinator
	- Set batch status in the debug file
	- Propagate SCVariables on reorg
	- Pipeline: Get SCVariables updates
		- Resolve #457
	- Fix off by 1 error in Pipeline.shouldL1L2Batch() (which shouldn't have
	  caused any problem, but it was not right)
- KVDB
	- Delete future checkpoints after reset
	- In `ResetFromSynchronizer`, remove all checkpoints first, and follow
	  the same logic as `reset()`.
- Cli
	- Add command to generate a BabyJubJub key pair (to be used for the
	  Coordinator Fee Account)
- Node
	- Adjust example config `Coordinator.L1BatchTimeoutPerc` to avoid
	  missing the L1Batch deadline with the following setup:
		- a block is mined every 2 seconds
		- single proof server that takes 2 seconds to calculate a proof
- TxProcessor
	- Close temporary pebble used for the exit tree after usage.
		- Resolve #463

cli/node/load-sk-example.sh

@@ -5,3 +5,6 @@ go run . --mode coord --cfg cfg.buidler.toml importkey --privatekey 0x30f5fddb34
 
 # Boot Coordinator
 go run . --mode coord --cfg cfg.buidler.toml importkey --privatekey 0xa8a54b2d8197bc0b19bb8a084031be71835580a01e70a45a13babd16c9bc1563
+
+# FeeAccount
+go run . --mode coord --cfg cfg.buidler.toml importkey --privatekey 0x3a9270c020e169097808da4b02e8d9100be0f8a38cfad3dcfc0b398076381fdd