Set in constructor of BaseParaSwapSellAdapter and validates before swap.
Created mock registry that only validates one address.
Changed the test fixtures to accomodate registry and added two new tests.
Updated deployment script.
Registry address left as a placeholder in package.json since not known yet.
Fixes MixBytes Warning 1.
Note that it didn't actually work as written since gasPrice was set too low
and also the verifyContract didn't work (so I had to verify it manually).
Deployed to mainnet at 0xC91864A5A1E2F52aDdfb69e31b89a3b7783733c3.
