Inefficient report processing

[rimutaka]

https://github.com/stackmuncher/stm_inbox/blob/master/stm_inbox_router/src/handler.rs is very inefficient:

• searching for project ID should be more adaptive - use most likely commits, the fewer the better
• adding commits - add what is likely to be missing, not the whole lot
• do not copy report files if they havn't changed (repeat submission)