Respect retries and master timeout when task resolves

Fixed 2 issues for the situation where a task resolves instead of rejects and the call to `shouldContinue` returns true
1. If the `masterTimeout` time has been exceeded, it will now reject the promise.
2. It will now check if there are retries remaining and reject if there are no retries remaining or else decrement remaining retries

Resolves [this issue](#16).