Removing redundant Synthetix reference from Synths

[jjgonecrypto]

Closes #579

[codecov]

Codecov Report

Merging #584 into develop will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #584      +/-   ##
===========================================
- Coverage    99.46%   99.46%   -0.01%     
===========================================
  Files           44       44              
  Lines         2798     2792       -6     
  Branches       395      395              
===========================================
- Hits          2783     2777       -6     
  Misses          15       15              

Impacted Files	Coverage Δ
contracts/MultiCollateralSynth.sol	100.00% <ø> (ø)
contracts/Synth.sol	98.82% <100.00%> (-0.07%)	⬇️

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[zyzek]

Looks good. Does this mean also that the Synth contract doesn't need Synthetix as a mock in setup.js?

synthetix/test/contracts/setup.js

Lines 475 to 479 in d67a779

	{
	contract: 'Synth',
	mocks: ['Issuer', 'Exchanger', 'FeePool', 'Synthetix'],
	deps: ['TokenState', 'ProxyERC20', 'SystemStatus', 'AddressResolver'],
	}, // a generic synth

[hav-noms]

LGTM anything else to add to this?