Find a nice way to remove this hack from Worker

[haydenshively]

// TODO TxManager isn't hooked into the Database logic, so we have
// to pass along the repay and seize addresses here
if (!String(c.ctokenidpay).startsWith("0x")) {
  const repay = `0x${await this._tCTokens.getAddress(c.ctokenidpay)}`;
  this._candidates[i].ctokenidpay = repay;
}
if (!String(c.ctokenidseize).startsWith("0x")) {
  const seize = `0x${await this._tCTokens.getAddress(c.ctokenidseize)}`;
  this._candidates[i].ctokenidseize = seize;
}

[haydenshively]

Not only is the data structure poor (sticking two differently-typed things into the ctokenidpay and ctokenidseize variables depending on circumstance) but we can also make this more efficient by keeping a mapping from id-> address in memory, rather than asking the database to retrieve it every single time. The mapping would only change when new markets are added or if the database is reset/reinitialized, in which case we'd be restarting the code anyway.