Add info to readme regarding class name length restriction

[MrHubble]

Thanks for the great gem.

One small issue I ran into. I had a class name that was 41 characters in length which resulted in an app[scheduler.1]: NameError: uninitialized constant on Heroku only (it seemed to work fine in development) when I added the active_scheduler gem.

When I renamed the class so it was now 29 characters in length I no longer received the error on Heroku.

Perhaps some info regarding class name size restrictions could be added to the readme if such a restriction does exist.

[JustinAiken]

• Hmm, don't suppose you have any way to reproduce this off of Heroku?
• Are you sure it was the size, and not something else in the name?

[MrHubble]

Unfortunately I can't replicate it off of Heroku. If it helps I changed the job name from CalculateAllVehicleServiceMetricValuesJob to CalculateAllServiceMetricsJob.

I'm fine if we just close this issue. I thought the name restriction might have been an undocumented feature.