Use sinon for fake timers in tests #137

Job	Run time
administrator-test	22m 57s
client-authentication-test	22m 21s
adversary-test	53m 21s
circuits-test	33m 45s
dependency-review	7s
eslint-check	3m 15s
ganache-erc1155-test	28m 42s
ganache-erc20-test	34m 43s
ganache-erc721-test	35m 23s
ganache-protocol-test	32m 36s
ganache-tokenisation-l2-test	29m 4s
general-tests	1m 24s
optimist-sync-test	29m 3s
periodic-payment-test	30m 50s
check apps for liveliness	26m 33s
check gas transactions per block	39m 39s
ping-pong-test	28m 33s
unit-test-circuits	7m 23s
unit-tests	34m 2s
x509-test	34m 25s
	8h 48m 6s

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