library shouldn't attempt to configure bluebird

[gavinsharp]

When trying to test a simple query, I got:
Error: cannot enable long stack traces after promises have been created

This exception was thrown by bluebird because my app created a promise before calling into node-redshift.

I eventually figured out I could work around this by passing { longStackTraces: false }, but I think that shouldn't be necessary - it's not uncommon for apps to be using promises elsewhere. I suggest making the default value of longStackTraces false, or removing it as an option altogether (library consumers can call Promise.config themselves if desired).

[gavinsharp]

Oh and thanks for the very useful library, by the way :)