Use transactions to fix socket update errors

[nwalters512]

As noted in the Sequelize docs, Sequelize uses a transaction internally for operations like findOrCreate, which is precisely the method that the active staff API uses when adding staff members. I believe this fact is causing #92 - there's a race condition where we try to read a tuple before the transaction that creates it has been committed. This PR modifies the code from sequelize-stream to make the options object available to event listeners so that we can use options.transaction as appropriate.

Closes #92 (just over a year after it was reported!)

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[james9909]

Since we're adding our own modified version of sequelize-stream, can we remove it as a dependency?

[nwalters512]

Yep, good call!

Would also be nice to contribute these changes back to sequelize-stream someday, but I don't think I have the bandwidth to do that now.