Code review comment for lp:~soliloque/simple-scan/batch-scan

Thanks! I committed with a few changes:
- I merged the build instructions in a separate merge - they don't relate to this change
- I renamed "speed" to "page delay"
- I changed the setting from us to ms (us seems overkill)
- I changed how the slider looks in the UI

The sleep looks fine since this is all running in its own thread.