Create exception handling model for Fluo observer and loader

Workers and loaders do not have a model for handling non-commit exceptions. Currently, both abort the transaction and just print an error. It would be nice to create a exception handling model that does the following:
1. Makes it visible for developers that an exception occurred
2. Provides enough information for developers to debug the exception
3. Allow developers to replay work that was being attempted when exception occurred.

A better model for handling exceptions could allow users to add sanity checks to their code using Guava's Preconditions.

The exception handling model doesn't need to complicated. It could be just a special log message that is printed that has a lot of debug information and state to replay work. This log message could be output the normal system logs as well as a special log could be used to replay work.